describing motion - mr. regan's educational...

Name Date Class

Describing Motion 1a. REVIEW A(n) is a place or

object used for comparison to determine if something is in motion.

b. EXPLAIN Why is it important to know if your reference point is

moving?

I get it! Now I know that an object is in motion if

I need extra help with

7B

When Is an Object In Motion?

Name Date Class

Describing Motion On a separate sheet of paper, explain why for thousands of years people believed that stars moved across Earth’s sky. Explain why we now have a different explanation of why stars move across the night sky. Be sure to mention reference points.

7C

Name Date Class

Describing Motion

1. Describe how you determine whether an object is in motion.

2. Explain why reference points that are stationary are usually chosen

to determine whether an object is in motion.

3. Give three examples of reference points that are stationary relative

to Earth.

4. When determining the motion of the planets in the solar system,

what is a good reference point to use? Explain.

5. Explain what centimeters, kilometers, and millimeters are.

6. motion

7. reference point

8. International System of Units

9. distance

a. the measurement system used by scientists b. the length of the path between two points c. changing position relative to another object d. a place or object used for comparison to

determine if an object is in motion

7D

Building Vocabulary Match each term with its definition by writing the letter of the correct definition in the right column on the line beside the term in the left column.

Understanding Main Ideas Answer the following questions in the spaces provided.

Name Date Class

Describing Motion Exploring Reference Points Depending on the reference point you choose, the same object can seem to be moving or standing still. Furthermore, even if an object seems to be moving from two different reference points, observers at those points might disagree about its speed and direction.

Here is a simple example: In the diagram below. A crow is flying along at a constant speed, carrying a ball. Suddenly, the crow accidentally drops the ball and watches it fall. The diagram shows the position of the crow and the ball at five points in time, one second apart. A person standing still on the ground also watches the ball fall.

1. From the reference point of the crow, in what direction is the ball falling? Does it appear to follow a curved or straight path? Explain.

2. How many seconds does it take the ball to fall to the ground? 3. The sides of the grid squares in the diagram are 10 meters long.

Using this, calculate the average speed of the ball during its fall from the point of view of the crow. About how fast was it traveling during the last second of its fall from this perspective?

4. From the reference point of the person on the ground, does the ball appear to fall in a straight or curved angle?

7E

Read the passage and study the diagram below. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Describing Motion Write the letter of the correct answer on the line at the left.

1. Jane is sitting in the family car. Her mother is driving her from their house to the library. Jane waves as she passes her friend Marina. Which of the following is not moving with respect to Jane? A Marina B the family car C the library D Jane’s house

3. Which of the following is the best

reference point for describing the motion of the planets in our solar system? A a space ship in orbit about Earth B the center of the Milky Way C Earth D the sun

2. Which is the best reason for not using a moving car as a reference point? A The car will get out of sight too quickly. B It is difficult to tell other people which car

you are using. C It is difficult to determine which direction

motion is occurring. D The car has moving parts, like rolling tires,

that can be distracting.

4. Jeff is in a stationary school bus.

Which is the best reference point for him to use to determine when the bus starts to move? A the front entrance of the school B the school bus sitting next to him C a car waiting to pick up another student D a student walking on the sidewalk

Fill in the blank to complete each statement.

5. The SI unit for measuring distance is the .

6. There are 1,000 in a meter.

7. There are 1,000 meters in a(n) .

8. An object is in if its position changes relative to another object.

9. A(n) is a place or object used for comparison to determine if something is in motion.

10. is the length of the path between two points.

7F

Name Date Class

Speed and Velocity 1a. IDENTIFY The (instantaneous/average) speed is the speed of the object

at a given instant in time. The (instantaneous/average) speed is the speed of the object over a longer period of time.

b. APPLY CONCEPTS The speedometer in a car gives the car’s speed.

I get it! Now I know to calculate the speed of an object, I need to


2. ANSWER How do you describe the motion of an object?

I get it! Now I know that the velocity of an object is


15B

How Do You Calculate Speed?

How Do You Describe Velocity?

Name Date Class

Speed and Velocity

3a. IDENTIFY The of a distance-versus-time graph

shows you the speed of a moving object.

b. CALCULATE The rise of a line on a distance-versus-time graph is 900 m

and the run is 3 min. What is the slope of the line?

c. APPLY CONCEPTS Is it possible for a distance-versus-time graph to be

a vertical line? Explain.

I get it! Now I know to show the motion of an object on a line graph, you


15C

How Do You Graph Motion?

Name Date Class

Speed and Velocity Amber walked to the swimming pool, stopping to talk to Maria on her way there. Amber walked at a constant speed of 100 m/min for the first four minutes; then she visited with Maria for three minutes; then walked for two more minutes at a constant speed of 75 m/min. In words, describe how a distance-versus-time graph of Amber’s progress would look.

15D

Name Date Class

Speed and Velocity On Saturday, Ashley rode her bicycle to visit Aileen. Aileen’s house is directly east of Ashley’s. The graph shows how far Ashley was from her house after each minute of her trip.

1. Ashley rode at a constant speed for the first 4 minutes of her trip. What was her constant speed?

2. What was her average speed for the entire trip?

3. What was her average velocity for the entire trip?

4. Ashley stopped to talk with another friend during her trip. How far was she from her house when she stopped?

5. What was Ashley’s instantaneous speed 5 minutes into her trip?

6. average speed

7. velocity

8. instantaneous speed

9. slope

10. speed

a. the distance an object moves per unit of time

b. total distance divided by total time

c. speed at a given point in time

d. speed in a given direction

e. the steepness of a line on a graph

15E

Understanding Main Ideas Use the following paragraph and graph to answer questions 1 through 5. Write your answers on a separate sheet of paper. Remember to include units in your answers.


Name Date Class

Speed and Velocity Describing Motion

• Point A to Point B: Walk 200 m north for 3 minutes.

• Point B: Stop to pet a neighbor’s dog for 1 minute.

• Point B to Point C: Walk fast to make up for the time you spent with the dog. Walk 100 m east for 1 minute.

• Point C to Point D: Jog 150 m northeast across the park for 1 minute.

• Point D to Point E: Walk east 200 meters for 1 minute.

• Point E: Stop to tie your shoe for 30 seconds.

• Point E to Point F: Walk north 100 m for 30 seconds and meet your friend, who is waiting for you.

1. What is the total distance you traveled? 2. What is the total time you traveled? 3. What is the average speed for your walk? 4. On a sheet of graph paper, make a map of the route that you

followed. Label all points and directions. Make sure that all distances are shown to the same scale.

5. On your map, connect Point A to Point F with a straight line. What does this line represent, and how does this distance compare to the distance you walked?

6. Make a graph to show your motion. Show time on the y-axis and distance on the x-axis.

15F

There are many ways to describe motion. You can write a description of the motion, like the steps shown below. You can make a map to show the path of the motion. And you can make a graph to show how the motion changes over time. Read the description of a walk to a friend’s house and complete the activity that follows.

Name Date Class

Speed and Velocity If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

1. On a distance-versus-time graph, a speed of zero would appear as a horizontal line.

2. The SI unit for speed is m/min.

3. A distance-versus-time graph will never show a horizontal line.

4. The slope of a line is found by multiplying the rise by the run.

5. On a distance-versus-time graph, a straight line indicates that an object’s speed is zero.

6. Speed in a given direction is called velocity.


7. A speedometer shows the speed of a vehicle.

8. To describe an object’s motion, you need to know both its speed and its .

9. The speed of an object is found by dividing the total distance by the total time.

10. Alfonso ran the 1,000-meter race in 2.5 minutes. Alfonso’s average speed was m/min.

15G

Name Date Class

Acceleration 1a. DEFINE The rate at which velocity changes is called b. INFER A softball has a (positive/negative) acceleration when it is

thrown. A softball has a (positive/negative) acceleration when it is caught.

c. EXPLAIN A girl skates around the perimeter of a circular ice rink

at a constant speed of 2 m/s. Is the girl accelerating? Explain.

I get it! Now I know that in science acceleration refers to


I get it! Now I know that the two types of graphs that you can use to analyze the motion

of an accelerating object are


21B

What Is Acceleration?

How Do You Graph Acceleration?

Name Date Class

Acceleration Compare and contrast the graphs of distance versus time and speed versus time.

21C

Name Date Class

Acceleration

1. In science, what three changes can each cause an object to accelerate?

2. What is the equation for finding the acceleration of an object

moving in a straight line?

3. Graph A below plots a race car’s speed for 5 seconds. What is the

car’s rate of acceleration?

4. Graph B below plots the same race car’s speed for a different 5-second

interval. What is the car’s rate of acceleration during this interval?

5. acceleration

21D


Building Vocabulary Write a definition for the term on the lines below

Name Date Class

Acceleration Exploring Changing Directions When an object speeds up or slows down, it is easy to understand that it has accelerated. But when an object moves at a constant speed and changes direction, it is harder to understand why this is also called an acceleration. Look at the figure below. Suppose an object is moving in a circle at a constant speed of 2.0 cm/s. When the object is at point A, it is moving to the right and if it continued to go in a straight line, it would move to point B. Instead, it moves along the circle to point C.

1. Measure the distance in centimeters from point A to point B. How far is it?

2. Measure the distance along the circle in centimeters from point A to point C. How far is it?

3. How far is the object from where it would have been if it had not been accelerated? (How far is it from B to C?)

4. Suppose the object at point A were moving at 4.0 cm/s. If it were not accelerated, where would it be after 1.0 second?

5. If the object moved along the circle at 4.0 cm/s, where would it be after 1.0 second?

6. Measure the distance in centimeters between the two points you indentify in Questions 4 and 5. How does this compare to the distance you measured in Question 3?

7. Suppose the circle has a circumference of 25.1 cm. Compare where the object would have been if it had gone in a straight line at 4.0 cm/s for 6.28 s (no acceleration) to where it is after it has gone around the circle for 6.28 s at 4.0 cm/s.

21E

Read the passage and examine the figure. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Acceleration If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

1. If a train is slowing down, it is accelerating.

2. To find the acceleration of an object moving in a straight line, you must calculate the change in distance for each unit of time.

3. A Ferris wheel turning at a constant speed of 5 m/s is not accelerating.

4. An airplane is flying west at 200 km/h. Two hours later, it is flying west at 300 km/h. Its average acceleration is 100 km/h2.

5. A speed-versus-time graph for a car’s motion is a horizontal line at a speed of 12 m/s. The car’s acceleration during this time is 12 m/s2.

6. The SI units for acceleration are km/h2.


7. The rate at which the velocity of an object changes is the object’s rate of .

8. An airplane is accelerating at 8 m/s2. Each second its speed increases by m/s.

9. An airplane is accelerating at –8 m/s2. The distance the airplane travels each second is than the distance it traveled during the previous second.

10. An amusement park ride falls straight down for 4 seconds. During this time, the ride accelerates from a speed of 0 m/s to 40 m/s. The ride’s rate of acceleration during the 4 seconds is m/s2.

21F

Name Date Class

The Nature of Force

I get it! Now I know that forces are described by


1a. CALCULATE You push on a desk with a force of 120 N to the right.

Your friend pushes on the same desk with a force of 90 N to the left. What is the net force on the desk?

b. PREDICT Your friend increases her force on the desk by 30 N. She doesn’t change the direction of her push. What happens to the net force on the desk? Will the desk accelerate?

I get it! Now I know that changes in motion are caused by


35B

How Are Forces Described?

How Do Forces Affect Motion?

Name Date Class

The Nature of Force You push on one side of an open door with a force of 120 N. Your friend pushes on the other side of the door with an equal force. On a separate sheet of paper, explain how these two forces affect the motion of the door.

35C

Name Date Class

The Nature of Force

change an object’s motion push or pull

do not change an object’s motion have direction

net force = 0 N net force does not equal 0 N

1.

2. newton

3. force

4. balanced forces

5. unbalanced forces

6. net force

a. the SI unit for force

b. sum of all forces acting on an object

c. push or pull

d. can change an object’s motion

e. will not change an object’s motion

35D


Understanding Main Ideas In the Venn diagram, write the phrases listed below to describe unbalanced forces and balanced forces. Write the characteristics shared by unbalanced and balanced forces in the area of overlap.

Unbalanced Forces

Balanced Forces

Name Date Class

The Nature of Force Net Force, Mass, and Change in Motion Unbalanced forces cause a chance in an object’s motion. The net force acting on the object causes it to speed up, slow down, or change direction. Changes in motion, that is, speeding up, slowing down, or changing direction, are called acceleration. When an object of a certain mass is acted upon by a net force, the amount of change in the object’s motion (its acceleration) is proportional to the size of the net force.

When two values are proportional, an increase in one causes the other value to increase or decrease. These relationships between proportional values are often in the natural world. For this reason, they have specific names.

Directly proportional: When the net force increases, the change in motion for an object of certain mass increases. Any two values that increase or decrease in the same way are directly proportional. Figure 1 shows a graph of this relationship.

Inversely proportional: Whenever an increase in one value results in a decrease in another value (and vice versa), the two values are inversely proportional. Figure 2 shows an inverse relationship for the amount of change in motion and mass.

Look at the table below that shows how net force, mass, and the change in motion are related.

1. On graph paper, plot each pair of values for mass and force from the table. Let the horizontal axis represent mass, and the vertical axis represent force. Connect the points with lines.

2. When acceleration is held constant and objects of different mass are observed, are mass and force directly proportional or inversely proportional? Explain.

35E

Read the passage, look at the diagrams to its right, and study the table below it. Then use a separate sheet of paper to answer the questions that follow the table.

If acceleration is: and mass is: force must be: 1 m/s2 0.1kg 0.1N 1 m/s2 0.2kg 0.2N 1 m/s2 0.5kg 0.5N 1 m/s2 0.7kg 0.7N 1 m/s2 1.0kg 1.0N

Name Date Class

The Nature of Force If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

1. Balanced forces do not change the motion of an object.

2. Forces cause some changes in motion.

3. A net force causes no change in an object’s motion.

4. If Manuel exerts a force of 10 N to push a desk to the right at the same time Lynn exerts a force of 15N to push the desk to the left, the desk will move to the left.


5. When you pull on a window shade, you exert a(n) .

6. A(n) can be used to represent the direction and strength of a force.

7. The strength of a force is measured in .

8. The net force determines how and if an object will .

9. When two forces act in opposite directions, the object will accelerate in the same direction as the force.

10. A force is described by its and by the direction in which it acts.

35F

Name Date Class

Friction and Gravity 1a. LIST Name four types of friction and give an example of each.

b. CLASSIFY What types of friction occur between your bike tires and the ground when you

ride over cement, through a puddle, and when you apply your brakes?

I get it! Now I know that friction is affected by


2a. DESCRIBE What happens to the gravitational force between two objects when their masses

are increased? What happens when the distance between the objects increases?

b. RELATE CAUSE AND EFFECT If the mass of Earth increased, what would happen to your

weight? What about your mass?

I get it! Now I know that factors that affect the gravitational force between

objects are


43B

What Factors Affect Friction?

What Factors Affect Gravity?

Name Date Class

Friction and Gravity On a separate sheet of paper, define friction and identify four types of friction.

43C

Name Date Class

Friction and Gravity

1. What are the two factors that affect the frictional force between two surfaces?

2. What two factors affect the gravitational force between two objects?

3. How does mass differ from weight? .

4. friction

5. rolling friction

6. sliding friction

7. fluid friction

8. static friction

9. weight

10. gravity

a. the force that pulls objects toward each other

b. the type of friction that exists between oil and a door hinge

c. the force that one surface exerts on another when two surfaces rub against each other

d. the type of friction that occurs when you rub sandpaper against wood

e. the type of friction that occurs when a wheel turns on a surface

f. a measure of the force of gravity on an object

g. the type of friction that occurs between objects that aren’t moving

43D



Name Date Class

Friction and Gravity The Great Pyramids The ancient Egyptians built pyramids out of large blocks of limestone. No one knows for sure how they managed to move the blocks across land.

One idea about how the Egyptians moved the stone blocks without modern machines is a simple one. Set a heavy book on a table. If you try pushing it with your little finger, it will be hard to do. Next, place five round pencils, parallel to each other, under the book and try again. This time you can move the book easily. You have replaced sliding friction with rolling friction. The force needed to overcome rolling friction is much less than the force needed to overcome sliding friction. Some people believe that the ancient Egyptians used this understanding of friction and moved the heavy stone blocks by placing a layer of wooden logs under the blocks. As the stone was pulled forward, the logs in back were picked up and placed in front of the block again, to provide a kind of friction-reducing track along which to roll the blocks of stone.

1. List two reasons why the limestone blocks of the pyramids were so difficult to push across land.

2. How might the Egyptians have been able to move the heavy stone blocks?

3. Can you think of another way the Egyptians might have tried to reduce friction to move the heavy blocks?

4. Historians know that large stone blocks can be dragged if logs are placed under them. Is the idea that the Egyptians built the pyramids by rolling stone blocks on logs a fact or a hypothesis?

43E

Read the passage and look at the diagram below it. Then use a separate sheet of paper to answer the questions that follow the diagram.

Name Date Class

Friction and Gravity Write the letter of the correct answer on the line at the left.

1. When you swim in a pool, A sliding friction occurs. B static friction occurs. C rolling friction occurs. D fluid friction occurs.

3. When you skateboard on a ramp,

A sliding friction occurs. B static friction occurs. C rolling friction occurs. D fluid friction occurs.

2. When you rub your palms together, A sliding friction occurs. B static friction occurs. C rolling friction occurs. D fluid friction occurs.

4. When you push a desk that doesn’t

move, A sliding friction occurs. B static friction occurs. C rolling friction occurs. D fluid friction occurs.


5. The states that the force of gravity acts between all objects in the universe that have mass.

6. As distance increases, gravitational force .

7. When you stand on a bathroom scale, it displays the that Earth is exerting on you.

8. Friction acts in a direction to the direction of the object’s motion.

9. When the irregularities of one surface come into contact with those of another surface, occurs.

10. The applied force required to push something across a surface as friction increases.

43F

Name Date Class

Newton’s Laws of Motion

I get it! Now I know that Newton’s first law of motion states that


1a. REVIEW What equation allows you to calculate the force acting on an

object?

b. CALCULATE What is the net force on a 2-kg skateboard accelerating

at a rate of 2 m/s2?

c. PREDICT If the mass of the skateboard doubled but the net force

on it remained constant, what would happen to the acceleration

of the skateboard?

I get it! Now I know that Newton’s second law of motion describes the relationship


51B

What Is Newton’s First Law of Motion?

What Is Newton’s Second Law of Motion?

Name Date Class

Newton’s Laws of Motion 2a. IDENTIFY A dog pulls on his leash with a 10-N force to the left.

Identify the reaction force.

b. ANSWER Using all three of Newton’s laws, explain how objects react to forces.

I get it! Now I know that Newton’s third law of motion states that


51C

What Is Newton’s Third Law of Motion?

Name Date Class


On a separate sheet of paper, write Newton’s first law of motion. Give examples to illustrate it.

51D

Name Date Class


1. Newton’s second law of motion describes the relationship among force, mass, and acceleration. Write the equation.

2. How does the diagram at the right illustrate Newton’s

third law of motion?

If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

3. If you increase the force on an object, its acceleration increases.

4. If you increase the mass of an object, its acceleration decreases.

5. To accelerate a 3 kg skateboard at 9 m/s2, a force of 3 newtons is needed.

6. The amount of inertia an object has depends on its speed.

7. inertia

51E

Understanding Main Ideas Answer the following questions in the spaces provided. Use a separate sheet of paper if you need more room.

Building Vocabulary Write a definition for the term on the lines below.

Name Date Class


Measuring Acceleration When you ride in a car that is accelerating, you can feel the acceleration, even if your eyes are closed. Sometimes however, you want to measure acceleration. Acceleration can be measured with an accelerometer. In this exercise, you will construct and experiment with the simple accelerometer pictured below. Just draw a protractor on a large card, showing angles measured from a vertical line. Attach one end of a string to the apex of these angles, and tie four or five large washers to its end. Mount the card and string vertically on a small stand. Once the accelerometer is assembled, practice using it. The instrument measures the acceleration when it is moved horizontally in a direction parallel to the card. The greater the acceleration, the greater the angle formed by the accelerometer’s string and vertical line. The point of greatest acceleration is represented by the largest angle. On a separate sheet of paper, make a data table with three columns. Label them: Activity, Greatest Acceleration Angle, and Observations. Next, perform the activities listed below and complete your table. For best results, have one person move the accelerometer while another watches and records the results.

• Begin to push the accelerometer across the table.

• From a standing start, begin walking.

• Observe the accelerometer while riding inside a car or bus. Watch the accelerometer as the vehicle begins to move from a complete stop.

• Observe the accelerometer while riding inside a moving car or bus. Watch the accelerometer as the vehicle slows to a complete stop.

1. Why didn’t the accelerometer maintain a constant angle during most

of these activities?

2. What is the greatest acceleration angle you observed? Do you think you would ever obtain a 90° angle?

51F

Read the passage, follow the directions for constructing an accelerometer, and use the accelerometer in the activity described. Then use a separate sheet of paper to answer the questions that follow activity description.

Name Date Class

Newton’s Laws of Motion If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

1. Newton’s first law of motion states that an object will not experience a change in motion unless acted upon by a(n) balanced force.

2. To increase acceleration of an object, you reduce its mass or increase the applied force.

3. Newton’s third law of motion states that if one object exerts a force on another object, then the second object exerts a force of equal strength in the same direction.

4. Resistance to change in motion is called stasis.

5. Action and reaction forces acting in opposite directions do cancel out because they act on different objects.

6. If you lean against a wall, the wall pushes back on you with a(n) weaker force.


7. Newton’s second law of motion states that an object’s acceleration depends on its and on the net force acting on it.

8. Acceleration is measured in .

9. Force is measured in a unit called the .

10. The smaller the mass of an object, the its inertia.

51G

Name Date Class

Momentum 1a. EXPLAIN How can a heavy moving van have the same momentum as a

small motorcycle?

b. CALCULATE What is the momentum of a 750-kg car traveling at a

velocity of 24 m/s?

c. INFER The total momentum of two marbles before a collision is

0.06 kg-m/s. No outside forces act on the marbles. What is the total

momentum of the marbles after the collision?

I get it! Now I know that momentum is conserved unless


55B

What Is an Object’s Momentum?

Name Date Class

Momentum On a separate sheet of paper, explain how the mass and velocity of a moving object affects its momentum. Include examples.

55C

Name Date Class

Momentum

1. What does it mean to say that momentum is conserved?

2. What is the momentum of a 20-kg dog running at a speed of 8 m/s?

3. Suppose you have two toy cars. Each has a mass of 0.04 kg. The cars have tape on their bumpers that will cause them to stick together. One car is stopped on the track. The other car, traveling at a velocity of 4 m/s, hits the first car. What is the momentum of the coupled cars? Show your calculations, and explain your answer.

4. momentum

5. law of conservation of momentum

55D


Building Vocabulary Write a definition for each of these terms on the lines below.

Name Date Class

Momentum Life-Saving Barrier On January 14, 1998, a former racing car driver by the name of John Fitch received an award for “his life-long contributions in the field of roadside safety.” Back in the late 1960s, Fitch had invented a device that is now used in all 50 states of the United States. The device is believed to have saved thousands of lives.

You’ve probably seen it—or, really, them—near the exit ramps of bridges and highways or other places where roadways divide. They are plastic, sand-filled barrels called Fitch Barriers. And their purpose is to slowly absorb the momentum of a vehicle that might otherwise be stopped dead by a solid wall or highway divider.

Study the drawings below. They show the mass and velocity of four different cars on a collision course with a concrete wall or Fitch Barriers.

1. Which car has the greatest momentum? What is its momentum? 2. Of the cars that strike the Fitch Barriers, which will penetrate the

least distance? Explain your answer. 3. Compare the forces exerted by the wall and the Fitch Barriers on Cars

A and B and describe differences, if any, about how those forces are applied.

55E

Read the passage and study the diagrams below it. Then use a separate sheet of paper to answer the questions that follow the diagrams.

Name Date Class

Momentum Write the letter of the correct answer on the line at the left.

1. Which of the following, moving at the same speed, would be hardest to stop? A car B fire engine C Frisbee D stroller

3. Which formula is used to calculate momentum? A Momentum = Mass × Speed B Momentum = Weight × Speed C Momentum = Volume × Velocity D Momentum = Mass × Velocity

2. Which moving object, in all likelihood, will have the greatest momentum? A volleyball hit by a fourth-grader B volleyball hit by an Olympic volleyball

player C volleyball hit by a senior adult D volleyball hit by a basketball coach

4. In which situation does the law of

conservation of momentum apply? A in the absence of greatest velocity B in the presence of least velocity C in the absence of outside forces D in the presence of outside forces


5. The total momentum of any group of objects remains the same unless outside forces act on the objects.

6. If outside forces such as friction are negligible, when two objects of the same mass collide and do not stick together, the objects multiply velocities.

7. Newton’s “quantity of motion” is conservation.

8. The less momentum an object has, the easier it is to stop.

9. Momentum, like velocity, is described by both a direction and a force.

10. The momentum of a 1000-kg vehicle traveling at a velocity of 25 m/s is 40kg × m/s.

55F

Name Date Class

Free Fall and Circular Motion

I get it! Now I know that free fall is


1a. IDENTIFY What is the force that causes objects to move in circles?

b. PREDICT If Earth’s gravity could be turned off, what would happen to satellites that are currently in orbit? Explain your reasoning.

I get it! Now I know that satellites stay in orbit because


59B

What Is Free Fall?

What Keeps a Satellite in Orbit?

Name Date Class


You swing a bucket of water in a vertical circle. The bucket falls as fast as the water, so the water stays in the bucket. On a separate sheet of paper, explain why. In your answer, compare the motion of the bucket to the motion of a satellite orbiting Earth.

59C

Name Date Class


1. What is the only force acting on an object in free fall?

2. Draw an arrow representing centripetal force in the diagram below.

3. In , an object falling from the top of a building accelerates at 9.8 m/s2.

4. A(n) follows a curved path in space around Earth.

5. causes an object to move in a circular path.

6. Together, satellites and ground receivers enable people using to pinpoint their geographic location.

59D


Building Vocabulary Fill in the blank to complete each statement.

Name Date Class

Free Fall and Circular Motion The Easy Way to Launch a Satellite Imagine that a professional baseball player can pitch a fastball at 90 mi/h. If he were on a train moving at 50 mi/h, and he threw his fastball in the same direction that the train was moving, the ball would travel at 140 mi/h. The pitch gets a “boost” from the train’s movement. In a similar way, rocket scientists get a boost in launching satellites by “throwing” them from a moving platform—Earth.

If you could look down on Earth from a point in space that is stationary relative to Earth’s rotation, you would see Earth rotating beneath you, from west to east. Every 24 hours, the same point on the surface would pass underneath you. The speed at which a point on Earth moves because of Earth’s rotation depends on how far that point is from the equator. A point on the equator rotates at a speed of a little less than 1,700 km/h. A point near the North Pole hardly moves at all in 24 hours, it just turns in a circle, like the center point of a fan.

In a way similar to the pitcher throwing his fastball, a rocket scientist can “throw” the rocket carrying the satellite toward the east, in order to take advantage of the rotation of the Earth. Cape Canaveral in Florida, where many satellites are launched, is traveling about 1,500 km/h. So instead of accelerating from zero, the satellite must be accelerated from 1,500 km/h to an orbital velocity of 19,200 km/h. That is still a lot of acceleration needed, but it is less than going from zero to 19,200 km/h.

1. Why can’t you feel Earth moving? 2. Some satellites move around Earth in polar orbits, that is, in a north

to south direction, rather than west to east. Can scientists who want to put a satellite into a polar orbit take advantage of Earth’s rotation to give the rocket a “boost”? Explain.

3. Imagine you wanted to launch a satellite so that it traveled in the opposite direction from usual, that is east to west, rather than west to east. How fast would the rocket launching that satellite have to travel, relative to the launch site, if you launched it from a point on the equator? Explain.

4. What would be the effect on satellites now in orbit if Earth were to stop rotating?

59E

Read the passage and study the diagram below it. Then use a separate sheet of paper to answer the questions that follow the diagram.

Name Date Class

Free Fall and Circular Motion Write the letter of the correct answer on the line at the left.

1. The state that exists when the only force acting on an object is gravity is called A free fall B inertia C acceleration D momentum

3. Satellites in orbit around Earth travel

in an almost circular path because Earth is A centripetal B free falling C curved D massive

2. The acceleration due to gravity near the surface of Earth is equal to A 9.8 m/s B 9.8 kg × m/s C 9.8 N D 9.8 m/s2

4. The word centripetal means A center seeking B gravitational C continuous D free falling


5. The force that causes an object to move in a circle is called .

6. Any object that travels around another object in space is a(n) .

7. An object traveling in a circle is accelerating because it is constantly changing .

8. is the centripetal force that causes a satellite to move in a circle.

9. Satellites in orbit around Earth continually fall toward .

10. If you could turn off a centripetal force, would cause the object to fly off in a straight line.

59F

Name Date Class

Work and Power 1a. DESCRIBE A waiter carries a 5-newton tray of food while he walks

a distance of 10 meters. Is work done on the tray? Why or why not?

b. EXPLAIN You’re holding your dog’s leash and trying to stand still as he pulls on the leash at an angle. You move forward. (All of/Some of/None of) his force does work on you.

c. CALCULATE How much work do you do when you push a shopping cart with a force of 50 N for a distance of 5 m?

I get it! Now I know that work is


I get it! Now I know that power


75B

How Is Work Defined?

What Is Power?

Name Date Class

Work and Power On a separate sheet of paper, give an example of doing work and tell how to calculate the amount of work done in the example.

75C

Name Date Class

Work and Power

1. The illustration shows a girl pushing on a heavy box. She pushes with a force of 40 N. How can you determine if she is doing work on the box?

2. The girl pushes the box 2 m. What formula should you use to

calculate the amount of work done on the box?

3. How much work does the girl do pushing the box 2 m?

4. work 5. joule 6. power

75D

Understanding Main Ideas Use the illustration to answer Questions 1–3 in the spaces provided.

Building Vocabulary On a separate sheet of paper, write a definition for each of these terms.

Name Date Class

Work and Power Exploring Work, Direction, and Weight In cases where the force is applied in exactly the same direction as the motion of the thing being worked upon, it is easy to calculate the amount of work performed. As the drawing shows, sometimes the force is applied at an angle to the movement of the object. When this happens, not all of the force contributes to the work being done. How do you calculate the amount of work when this happens?

The fraction of the applied force that actually contributes to the work depends upon the angle formed by the direction of the force and the direction of the object’s motion. For example, in the drawing the force of the person pulling the sled is at a 60° angle to the sled’s movement. Only part (0.5) of that force contributes to the work, as the table shows. Knowing this, it is easy to calculate the total work:

10 N (the force exerted) × 0.5 (the fraction of the force doing work) × 5 m (the distance moved) = 25 J Each row of this table gives information about a situation where force is applied to an object to cause movement, including the fraction of the force that contributes to the movement. Calculate the amount of work performed and complete the last column.

6. As the angle between the direction of the input force and the direction of movement increases from 0° to 90°, what happens to the fraction of the force that contributes to the work?

7. Why was no work done in the situation on line five of the table? 8. Did you need to know the mass of the moving objects to calculate

the amount of work?

75E

Read the passage below. Then complete the table and use a separate sheet of paper to answer the questions that follow the table.

Angle Between Direction of Force and Movement

Total Force (N)

Fraction of Force Doing Work

Distance Moved (m)

Total Work (J)

0° 10 1.0 5 1. 30° 10 0.87 5 2. 45° 10 0.71 5 3. 60° 10 0.5 5 4. 90° 10 0 5 5.

Name Date Class

Work and Power Fill in the blank to complete each statement.

1. Work divided by time equals .

2. The unit of work is the .

3. The unit of power is the .

4. Force multiplied by distance equals .


5. Work is done on an object when the object moves in the same direction in which the force is applied.

6. If you pull at an angle instead of in the direction in which the object moves, more of your force does work.

7. The farther you move an object, the more work you do.

8. The more power you use to move an object, the more work you do.

9. If you lift a box from the floor to a height of 1 m and then carry the box for 10 m, you do work only when you carry the box.

10. Power is the rate at which work is done.

75F

Name Date Class

Understanding Machines 1a. LIST Name two examples of machines for which the output force is

greater than the input force.

b. APPLY CONCEPTS Suppose that you use a pair of chopsticks and apply a force of 1 N over a distance of 0.01 m. How much work do you do? If the output force of the chopsticks is only 0.5 N, how far do the tips of the chopsticks move?

I get it! Now I know that machines make work easier by


I get it! Now I know that mechanical advantage


83B

What Does a Machine Do?

What Is Mechanical Advantage?

Name Date Class

Understanding Machines 2a. RELATE CAUSE AND EFFECT Real machines have an efficiency of less

than 100% because some work is wasted to overcome

b. PREDICT What happens to the efficiency of a bicycle as it gets rusty? What must you do to maintain the same amount of output work?

I get it! Now I know that efficiency


83C

What Is Efficiency?

Name Date Class

Understanding Machines

On a separate sheet of paper, describe the three ways a machine can help you do work and tell why machines are not 100 percent efficient.

83D

Name Date Class

Understanding Machines

1. The work of pulling the box will be easier if the man uses the ramp.

2. The ramp helps the man do work by reducing distance.

3. To calculate the efficiency of the ramp, divide the output work by the input work and multiply the result by 100%.

4. The ideal mechanical advantage of the ramp is its mechanical advantage with friction.

5. A machine’s is the number of times the machine multiplies the input force.

6. The force you exert on a machine is called the .

83E

Understanding Main Ideas In the illustration below, the man can either pull the box upward onto the platform or pull the box up the ramp. Use the illustration to answer Questions 1–4. If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.


Name Date Class

Understanding Machines An Ancient Machine Ancient societies did not have machines that ran on electric current, coal, or gasoline. Ancient engineers needed to use the energy generated from human and animal muscles as efficiently as possible. One ancient machine is the treadmill, a hollow wheel, large enough for someone to stand inside.

In the example below, a treadmill is used to lift water from a well. As the man tries to walk up the curved inner surface of the wheel, the force of gravity pulls his body back to the bottom and turns the wheel. The work performed by the man in the wheel turns an axle that drives a belt to move buckets down into a well, where they fill with water, and then come back up. The man turning the wheel supplies the input force, and water is pulled up from the well by output force. In this example, the man weighs 740 N. With each step, he raises his body 0.5 m, and is pulled back down by the force of gravity. Each step that he takes causes the conveyor to lift 7400 N of water a distance of 0.05 m.

1. Gravity pulls objects downward. How much work is performed when gravity pulls the man down 0.5 m after each step?

2. How much work is done to lift 7400 N of water in the well 0.05 m? Compare this to the work done by the man in the treadmill.

3. What is the input force exerted by the man inside the wheel? What is the output force exerted upon the water rising from the well? What is the mechanical advantage of this machine?

4. Calculate the efficiency of this treadmill. Is this likely? What factor might cause a real treadmill to be less efficient?

83F

Read the passage below. Then use a separate sheet of paper to answer the questions that follow. Show your calculations.

Name Date Class

Understanding Machines Fill in the blank to complete each statement.

1. Machines are devices that allow you to do in an easier way.

2. The force you exert when you use a machine is the .

3. The force exerted by the machine is the .

4. The force you exert on an object multiplied by the distance the object move is equal to , which is expressed in joules.

5. Divide output work by input work and multiply by 100% to find a machine’s .


6. A machine’s mechanical advantage is the output force multiplied by the input force.

7. If the output fore is greater than the input force, the mechanical advantage of the machine is greater than one.

8. If the machine increases distance, the output force is greater than the input force.

9. If a machine changes the direction, but not the amount of the input force, the MA is greater than 1.

10. An ideal machine has no friction.

83G

Name Date Class

Inclined Planes and Levers 1a. LIST List three closely related simple machines in the inclined

plane family.

b. EXPLAIN A simple inclined plane makes work easier by decreasing the input (force/distance) required to move the object.

c. COMPARE AND CONTRAST Name one way inclined planes and screws are similar and one way they are different.

I get it! Now I know that inclined planes

I need extra help with 2a. DESCRIBE Describe how each class of lever makes work easier.

b. CALCULATE What is the mechanical advantage of a lever with 2 m between the input force and the fulcrum and 1 m between the output force and the fulcrum?

c. INFER What class(es) of lever could the lever from the previous question be? Explain.

I get it! Now I know that levers are classified by


91B

How Do Inclined Planes Work?

How Are Levers Classified?

Name Date Class

Inclined Planes and Levers On a separate sheet of paper, explain how to increase the mechanical advantage of inclined planes and levers.

91C

Name Date Class

Inclined Planes and Levers

1. How does an inclined plane help you do work?

2. How is a screw related to an inclined plane?

3. Give an example of each of the three classes of levers.

4. inclined plane

5. wedge

6. lever

7. screw

8. fulcrum

a. the fixed point that a lever pivots around

b. a flat, sloped surface

c. an inclined plane wrapped around a cylinder

d. an inclined plane or two inclined planes back-to-back that can move

e. a rigid bar that is free to pivot, or rotate, on a fixed point

91D



Name Date Class

Inclined Planes and Levers Archimedes Screw Archimedes screw is a machine that can be used to raise water from a lower level to a higher level. For example, water can be taken out of a river, even when the water is low, and moved to irrigation ditches so that farm crops can be watered.

The device is a screw inside a cylinder. The screw is able to turn within the cylinder. The top and bottom of the cylinder are open. The bottom of the screw is submerged in the water and the screw is turned. The turning screw scoops up water and raises it along the surface of the screw thread. When the water reaches the top of the screw, it spills out of the cylinder into a duct or channel and is carried to where it will be used.

In some forms of the Archimedes screw, the screw and the cylinder turn together. In other forms, instead of a screw, the device is a coiled tube.

A small Archimedes screw can be turned by hand. Larger screws, such as those used for irrigation, are turned by other machines. In the Netherlands, windmills provide the power to turn Archimedes screws that remove water from low-lying farmland.

1. Why does the screw have to be inside a cylinder?

2. What information would you need in order to calculate the mechanical advantage of an Archimedes screw?

3. The height to which an Archimedes screw can raise water is limited because the device must be used at a low angle, no higher than 45° above the surface of the water. Why can’t the device be used in a vertical position?

4. What other materials might an Archimedes screw be able to move?

91E

Read the passage below. Then answer the questions that follow in the spaces provided.

Name Date Class

Inclined Planes and Levers If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

1. The ideal mechanical advantage of a an inclined plane is the length of the plane divided by its force.

2. When you use a wedge, instead of moving an object along the inclined plane, you move the inclined plane itself.

3. The thicker the wedge, the greater its mechanical advantage.

4. In a first-class lever, the fulcrum is between the input force and the output force

5. A knife is an example of a lever.

6. The lower arm acts like a first-class lever when it bends at the elbow.

Write the letter of the correct answer on the line at the left.

7. A flat, sloped surface is called a(n) A lever B screw C fulcrum D inclined plane

9. The threads of a screw act like a(n) A lever B wedge C inclined plane D fulcrum

8. A device that is thick at one end and thin at the other end is a A wedge B screw C lever D fulcrum

10. The fixed point that a lever pivots

around is the A fulcrum B plane C screw D wedge

91F

Name Date Class

Putting Machines Together 1a. LIST List two examples of a wheel and axle. Which of your examples

has the greater mechanical advantage?

b. APPLY CONCEPTS You exert a 100-N force on a pulley system to life 300 N. What’s the mechanical advantage of this system? How many sections of rope support the weight?

I get it! Now I know that pulleys and wheels and axles


2a. CALCULATE What is the mechanical advantage of a pencil sharpener

made from a wheel and axle with a mechanical advantage of 3 and a wedge with a mechanical advantage of 4?

b. ANSWER Explain how simple and compound machines make it easier to

do work.

I get it! Now I know that compound machines


97B

What Simple Machines Make Use of Turning?

How Does a Compound Machine Do Work?

Name Date Class

Putting Machines Together

On a separate sheet of paper, describe the three types of pulleys.

97C

Name Date Class

Putting Machines Together

1. What are the two types of machines that turn?

2. What are the three types of pulleys?

3. How do you find the mechanical advantage of a wheel and axle?

4. How does a compound machine increase force?

5. How do you find the mechanical advantage of a compound machine?

6. pulley

7. wheel and axle

97D



Name Date Class

Putting Machines Together A Compound Machine

A bicycle is made up of many simple machines. The brakes on a bicycle are levers that apply pressure to the wheel rims. Friction between the brake pad and the wheel rim slows the rate at which the wheels turn until you stop. You engage the brake levers by pulling on the levers attached to the handlebar. The levers on the handlebar are attached to a cable that pulls on the levers, which press on the wheel rim.

If a bicycle has quick-release wheels, the release mechanism is a lever. When you lift the lever, it disconnects the wheel so that you can remove it and fix a flat tire easily. When you put the wheel back on the bicycle, the lever securely locks the wheel in place.

A bicycle has more wheels than those it rides on. Your feet make circles as they turn the pedals and the axle to which the pedal crank is attached. You exert force over a wheel to turn the axle. The axle of the pedals turns the front gear. Another wheel that is attached to a chain turns the rear gear. The rear gear turns an axle. This axle turns the rear wheel of the bicycle. The force to the pedals is transmitted through all these machines to the rear wheel, which turns and pushes the bicycle forward.

1. Why are the brake and shift levers on the handlebar even though they control functions not located near the handlebars?

2. Why is the mechanical advantage provided by a lever important in a quick-release bicycle wheel?

3. Is the bicycle a machine to increase force or distance? Explain your answer. (Hint: Compare the size of the pedal “wheel” to the size of the bicycle wheel.)

97E

Read the passage and look at the diagram below it. Then use a separate sheet of paper to answer the questions that follow the diagram.

Name Date Class

Putting Machines Together Fill in the blank to complete each statement.

1. One of the simple machines that turns is the wheel and .

2. A single fixed pulley changes the of a force.

3. A system of fixed and pulleys is called a block and tackle.

4. A screwdriver and a doorknob are examples of a(n) .

5. In a compound machine, the of one simple machine becomes the input force of another simple machine.


6. If a compound machine is made of a pulley with a mechanical advantage of 3 and a wheel and axle with a mechanical advantage of 5, the mechanical advantage of the compound machine is 8.

7. To find the mechanical advantage of a wheel and axle, multiply the radius of the wheel by the radius of the axle.

8. To find the mechanical advantage of a pulley, count the sections of rope that support the object.

9. A bicycle is a compound machine because it contains more than one simple machine.

10. The part of a wheel and axle with the smaller radius is the wheel.

97F

Name Date Class

What Is Energy?

I get it! Now I know that since the transfer of energy is work, then power is


1a. IDENTIFY The energy an object has due to its motion is called

(kinetic/potential) energy. Stored energy that results from the position or shape of an object is called (kinetic/potential) energy.

b. SUMMARIZE What are the two factors that affect an object’s

kinetic energy?

c. APPLY CONCEPTS What type of energy does a cup sitting on a table

have? Why?

I get it! Now I know that the two basic types of energy are


113B

How Are Energy, Work, and Power Related?

What Are Two Types of Energy?

Name Date Class

What Is Energy? On a separate sheet of paper, describe the two basic kinds of energy and explain how energy and power are related.

113C

Name Date Class

What Is Energy?

1. How are work and energy related?

2. How is power related to energy?

3. What are the two basic kinds of energy?

4. A girl who weighs 30 kg is inline skating at a speed of 5 m/s. What is

the girl’s kinetic energy?

5. A hat that weighs 5 newtons is hanging from a hook 1.5 meters

above the floor. How much gravitational potential energy does the hat have?

6. energy

7. kinetic energy

8. potential energy

9. gravitational potential energy

10. elastic potential energy

a. potential energy related to an object’s height b. the ability to do work or cause change c. energy associated with objects that can be compressed or

stretched d. the energy an object has due to its motion e. energy that results from an object’s position or shape

113D



Name Date Class

What Is Energy?

The Come-Back Can Materials coffee can with plastic lid rubber band metal nuts 2 nails string file Procedure

1. Use a nail to punch a hole in the center of the bottom of the can and another in the center of the lid. File down the rough edges.

2. Use string to tie several nuts to the middle of the rubber band. 3. Slip one end of the rubber band through the hole in the bottom of

the can. Slide a nail through the rubber band to secure the rubber band to the can. Repeat this process with the lid. Put the lid on the can. The rubber band should just reach both ends of the can without being stretched too tightly.

4. Gently roll the can on a hard, level floor. Once the can reaches the end of its path, it will begin to roll back to you.

Analyze and Conclude

1. When you roll the can along the floor, the rubber band twists. What kind of energy is in the twisted rubber band?

2. Why does the can stop before it begins to roll back to you? 3. What do you think happens to the rubber band as the can rolls back

to you? 4. What kind of energy does the can gain as it rolls back to you? 5. What kind of energy are you adding to the can and rubber band

when you first push the can? 6. If you were to push the can harder, what effect would this have on

the energy in the rubber band?

113E

In even a simple action, energy is often transformed from one type into another (and back again). Follow the steps in the procedure. Then use a separate sheet of paper to answer the questions that follow it.

Name Date Class

What Is Energy? Write the letter of the correct answer on the line at the left.

1. The kinetic energy of an object is equal to one half its mass multiplied by its speed A squared B cubed C to the fourth power D to the fifth power

3. Energy is the ability to do work or

cause A events B change C friction D explosions

2. The gravitational potential energy of an object is equal to its weight multiplied by its A depth B height C volume D diameter

4. Energy and work are measured in

A newtons B joules C hertz D kilograms


5. When you do work on an object, some of your energy is to that object.

6. Power is the rate at which energy is .

7. Potential energy results from the or position of an object.

8. A stretched rubber band has energy.

9. A change in an object’s speed has a(n) effect on its kinetic energy than a change in its mass.

10. A mountain climber at the peak has energy.

113F

Name Date Class

Forms of Energy 1a. DEFINE Mechanical energy is the form of energy associated

with the , , or of an object.

b. CALCULATE At a certain point the kinetic energy of a falling apple is

5.2J and its potential energy is 3.5J. What is its mechanical energy?

c. INFER If an object’s mechanical energy is equal to its potential

energy, how much kinetic energy does the object have? Explain.

I get it! Now I know you can find an object’s mechanical energy by


2a. EXPLAIN Why do the particles of objects have both kinetic and

potential energy?

b. CLASSIFY The energy you get from eating a peanut butter and jelly sandwich is in the form of energy.

I get it! Now I know the forms of energy associated with the particles of objects

include


119B

How Can You Find an Object’s Mechanical Energy?

What Are Other Forms of Energy?

Name Date Class

Forms of Energy On a separate sheet of paper, list five forms of energy associated with the particles of an object. Identify each form as a type of potential energy, kinetic energy, or both (depending on whether it is moving or stored).

119C

Name Date Class

Forms of Energy

1. How can you determine an object’s mechanical energy?

2. Name two forms of energy associated with the particles that make

up objects.

a. mechanical energy

b. electrical energy

c. thermal energy

d. nuclear energy

e. chemical energy

f. electromagnetic energy

3.

4. 5.

6. 7. 8.

119D


Building Vocabulary Match each illustration with the correct form(s) of energy by writing the letter or letters of the form(s) of energy on the line at the left.

Name Date Class

Forms of Energy

The Cost of Electrical Energy You know that the watt (W) is a unit of power and that a kilowatt (kW) is 1,000 watts. The unit used by electric companies to measure the energy you use in your home is called the kilowatt-hour (kWh). One kilowatt-hour is 1,000 watts of electrical energy used for 1 hour.

Each electrical appliance in your home uses a different amount of electrical energy. The cost of operating an appliance is determined by the power rating of the appliance, the number of hours it is used, and the cost of the electrical energy.

To calculate the cost of operating an appliance, you must first determine the energy used in kilowatt- hours. To do this, multiply the power rating (watts) of the appliance by the number of hours you use the appliance, then divide that number by 1,000. For example, a 100-watt light bulb used for 5 hours a day would use 0.5 kWh per day

u§ ·¨ ¸© ¹

100 W 5 h= 0.5 kWh

1,000

If you are paying $0.10 per kWh, then the cost of using that light bulb for 1 day would be 0.5 kWh × $0.10, or $0.05.

1. What is the total cost of running all the appliances above for your family for one day? What is the total cost for one week?

2. Discuss three things that people in the family could do to reduce their electric bill.

119E

Read the passage below. Then fill in the table, using $0.10 per kWh to calculate the cost of running each appliance for one day. Answer the questions that follow on a seperate sheet of paper.

.

Appliance Estimated Time Used (h) Cost ($) Cost ($)

Microwave oven 1,500

Electric stove/oven 12,000

Clothes dryer 5,000

Vacuum cleaner 600

Clothes washer 500

Color television 200

Dishwasher 1,300

Name Date Class

Forms of Energy Write the letter of the correct answer on the line at the left.

1. To find an object’s mechanical energy, you add its A kinetic and potential energy B kinetic and thermal energy C potential and thermal energy D kinetic and chemical energy

3. Nuclear fusion reactions occur in

A nuclear power plants B a microwave oven C a match that is struck D the sun

2. A form of energy NOT associated with the particles of objects is A thermal energy B mechanical energy C nuclear energy D chemical energy

4. The total potential and kinetic energy

of the particles of an object is the object’s A nuclear energy B electromagnetic energy C thermal energy D mechanical energy


5. Mechanical energy is associated with the motion, position, or of an object.

6. Electromagnetic energy travels through space in the form of .

7. Lightning is a form of energy.

8. The breaking of bonds in food releases energy for your body to use.

9. The the temperature of an object, the lower its thermal energy.

10. Electrical energy is the energy of .

119F

Name Date Class

Energy Transformations and Conservation 1a. DEFINE A change in one form of energy to another form of energy is

called a(n)

b. RELATE CAUSE AND EFFECT When you turn on an iron, energy is transformed into energy.

c. APPLY CONCEPTS Describe the energy transformations that occur in a

waterfall.

I get it! Now I know that all forms of energy can be transformed into


2a. ANSWER How is energy conserved in a transformation?

I get it! Now I know that according to the law of conservation of energy, energy


125B

How Are Different Forms of Energy Related?

What Is the Law of Conservation of Energy?

Name Date Class

Energy Transformations and Conservation

On a separate sheet of paper, describe a single transformation of energy from one form into another. Explain whether there is more or less energy after the transformation has occurred.

125C

Name Date Class

Energy Transformations and Conservation

1. An energy transformation is occurring only at point 3.

2. In this example, the law of conservation of energy says that the ball never loses kinetic energy.

3. As the ball rises from point 1 to point 3, it slows down.

4. The ball has the most potential energy at point 3.

5. The ball has the least kinetic energy as it leaves point 2.

6. energy transformation

7. law of conservation of energy

125D

Understanding Main Ideas Study the illustration below and then read the following statements. If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.


Name Date Class

Energy Transformations and Conservation Orbits, Ellipses, and Energy Planets and comets orbit the sun in ellipse-shaped paths. While they orbit the sun, they respond to the sun’s gravitational pull. The farther away from the sun an object is, the less the sun’s gravity attracts it, and the slower that object moves in its orbit. The energy of a comet at its slowest position is similar to that of a pendulum at the very top of its swing. As the comet moves toward the sun, it gains speed until, at its closest approach to the sun, it is traveling at maximum speed. The energy of a comet at this position is similar to that of a pendulum at the bottom of its swing. Then, the comet moves past the sun, slowing down as it moves farther into space. A comet will follow the same orbit for many hundreds or thousands of years, speeding up and slowing down, orbiting the sun many times.

The diagram below shows the orbit of a comet around the sun. Point A is farthest from the sun and point E is closest to the sun. The comet moves counterclockwise.

1. At what point in its orbit does the comet have the greatest potential energy? At what point does it have the least potential energy?

2. At what point in its orbit does the comet have the greatest kinetic energy? At what point does it have the least kinetic energy?

3. Describe the energy transformations that are taking place as the comet moves from point B to point D.

4. Describe the energy transformations that are taking place as the comet moves from point F to point G.

5. What happens to the comet’s total energy when it is closest to the sun?

6. What happens to the comet’s total energy when it is farthest from the sun?

125E

In a swinging pendulum, potential energy is transformed to kinetic energy and back. The movement of planets and comets around the sun also shows the relationship between potential and kinetic energy. Read the passage. Then examine the diagram below it, and use the diagram to answer the questions that follow on a separate sheet of paper.

Name Date Class

Energy Transformations and Conservation Fill in the blank to complete each statement.

1. All forms of energy can be into other forms of energy.

2. A change from one form of energy to another is called a(n) .

3. When you use a match to light a candle, multiple of energy occur.

4. The law of of energy tells how much energy is present after electromagnetic energy changes to sound.

5. Whenever a moving object experiences friction, some of its kinetic energy is changed into energy.

6. Your body changes chemical energy into energy when you walk upstairs.

Write the letter of the correct answer on the line at the left.

7. Fusion reactions in the sun change nuclear energy into A mechanical energy B chemical energy C electromagnetic energy D potential energy

9. A baseball in play has its lowest

gravitational potential energy A when it is at its highest point B before it hits the ground C when the bat contacts it D after it hits the ground

8. In a pendulum, a continuous change occurs between kinetic energy and A potential energy B electromagnetic energy C thermal energy D mechanical energy

10. Energy can be neither destroyed nor

A created B transformed C changed D transferred

125F

Name Date Class

Temperature, Thermal Energy, and Heat

I get it! Now I know that temperature is related to


1a. LIST What are two factors that determine an object’s thermal energy?

b. Object A has less thermal energy than Object B, but heat

flows from Object A to Object B. What conditions would make this

possible?

I get it! Now I know that the thermal energy in an object is defined as


139B

What Determines the Temperature of an Object?

What Is Thermal Energy?

CHALLENGE

Name Date Class

Temperature, Thermal Energy, and Heat On a separate sheet of paper, compare and contrast melting 10 kg of ice with freezing 1 kg of water. Be sure to address temperature, heat flow, and thermal energy.

139C

Name Date Class

Temperature, Thermal Energy, and Heat

1. Two glasses of water have the same thermal energy. Must they have the same temperature? Explain.

2. Describe what is meant by absolute zero.

3. List the three things that determine thermal energy.

4. Compare the freezing point of water on the Celsius and the Fahrenheit temperature scales.

5. Compare a change in temperature of 1°C to a change of 1°F.

6. Celsius

7. temperature

8. heat

9. absolute zero

a. on this scale, water boils at 100 degrees

b. a measure of the average kinetic energy of the individual particles in an object

c. the transfer of thermal energy from a warmer object to a cooler one

d. the temperature at which no more thermal energy can be removed from an object

139D



Name Date Class

Temperature, Thermal Energy, and Heat Converting Temperatures In this section, you learned that most of the world uses the Celsius temperature scale, but that in the United States, the most common temperature scale is Fahrenheit. You are probably more familiar with one of these scales than the other. One way to become more comfortable with the unfamiliar temperature scale is to compare the numerical values of everyday temperatures in °C and °F.

Convert the following temperatures using the methods described above.

1. Normal body temperature is 98.6°F. °C

2. Room temperature is about 72°F. °C

3. The lowest temperature ever recorded on Earth was −89.4°C at Vostok, Antarctica. °F

4. The highest temperature ever recorded on Earth was 57.8°C at El Azizia, Libya. °F

5. −40°C = °F

6. The common temperature for baking a cake is 350°F. °C

7. Iron melts at 1535°C. °F Answer the following questions on a separate sheet of paper.

8. Which is warmer −30°C or −30°F? Show your work. 9. You are riding to school on a bus in a snowstorm. Through the

window, you see a lighted sign that gives the temperature as 26°, but you cannot make out whether the temperature scale is Celsius or Fahrenheit. Which is it, and how do you know?

139E

Read the passage and study the table.

To convert °F to °C To convert °C to °F 1. Subtract 32. 1. Multiply by 9. 2. Multiply by 5. 2. Divide by 5. 3. Divide by 9. 3. Add 32.

Name Date Class

Temperature, Thermal Energy, and Heat If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

1. At the freezing point, the particles in an object have no kinetic energy.

2. On the Celsius temperature scale, there are no negative numbers.

3. The more particles an object has at a given temperature, the more thermal energy it has.

4. Object A is much larger than Object B, but both are made of the same material. If both objects are at the same temperature, the thermal energy of Object A is the same as the thermal energy of Object B.

5. When heat is absorbed by an object, the speed of the particles in the object is unchanged.


6. The transfer of thermal energy from a warmer object to a cooler object is called .

7. is a measure of the average kinetic energy of the individual particles in an object.

8. Most of the world uses the temperature scale.

9. On the temperature scale, water boils at 212°.

10. The amount of thermal energy in an object depends on its , the number of particles in it, and how those particles are arranged.

139F

Name Date Class

The Transfer of Heat 1a. CLASSIFY What type of heat transfer occurs when eggs cook in a

hot pan? Before toasters, people toasted bread by holding it over

a fire. What type of heat transfer occurred then? Name the third

type of heat transfer and an example of food cooked by it.

b. ANSWER How does heat flow from one object to another?

I get it! Now I know that the three methods of heat transfer are


143B

How Is Heat Transferred?

Name Date Class

The Transfer of Heat On a separate sheet of paper, explain all of the heat transfer that occurs when a pot of soup on a metal grill is heated over a campfire and gets close to boiling. Be sure to mention convection currents.

143C

Name Date Class

The Transfer of Heat

Heat Transfer Example Method of Heat Transfer

An entire lake is heated by water from a hot spring at the bottom of the lake. 1.

Sunlight melts a wax crayon left outside. 2.

A burner on a stove heats the bottom of a pan. 3.

The inside frame of your front door feels cold during winter. 4.

A kite rises high above a hot, sandy beach. 5.

You feel the warm glow of a bonfire. 6.

7. convection

8. radiation

9. convection current

10. conduction

143D

Understanding Main Ideas Fill in the spaces in the table below by writing whether the heat is transferred by convection, radiation, or conduction.


Name Date Class

The Transfer of Heat Radiating Heat Internal combustion engines transform thermal energy to mechanical energy. Unfortunately, not all of the thermal energy produced by the burning of the mixture of fuel and air can be used to move the pistons. Some of the heat produced just heats the engine, and that can create problems. If an engine gets too hot, the oil that lubricates the moving parts will burn. Also, engines have some parts that will be destroyed if they get too hot.

A solution is to build a cooling system to carry heat away from the engine. The simplified diagram below shows a cooling system for an automobile engine. Arrows indicate the direction of movement of cooling fluid. Internally, the radiator is a series of flattened pipes that the cooling fluid moves through. The flattened pipes provide a very large surface area over which outside air flows.

1. Where is the cooling fluid hotter, in tube A or in tube B? Why? 2. Heat moves from material having more thermal energy to material

having thermal energy. Into what material does heat from the hot cooling fluid go?

3. What is the function of the radiator? 4. The pump moves fluid from the radiator into the engine. What might

happen to the engine if the pump stopped working?

143E

An automobile engine would not be able to run for very long if it did not have a cooling system. Read the passage and examine the diagram. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

The Transfer of Heat Write the letter of the correct answer on the line at the left.

1. Water bubbles up through a hot spring at Yellowstone National Park. What method of heat transfer is this? A conduction B convection C radiation D specific heat

3. The inside window pane in your house

feels very cold to touch on a winter night. Why does it feel cold? A The cold from the outside is flowing in by

convection. B The warm from the inside is flowing out by

convection. C The cold from the outside is being

conducted to the inside. D The warm from the inside is being

conducted to the outside.

2. On a sunny day, you return to your car after a ball game. The inside of the car is very hot. How did the car get so warm? A conduction B convection C radiation D specific heat

4. Malia burned herself when she picked

up a hot iron skillet from the stove. What method of heat transfer caused the burn? A conduction B convection C radiation D specific heat


5. Heat is transferred directly from one particle of matter to another by the process of .

6. A circular flow of warmer fluid and cooler fluid is called a(n) .

7. Heat is always transferred from areas.

8. is the transfer of energy by electromagnetic waves.

9. Heat that is transferred by the movement of currents within a fluid is called .

10. The only form of heat transfer that does not require matter is .

143F

Name Date Class

Thermal Properties 1a. CLASSIFY Foam picnic coolers keep food cold on a hot day. Is foam a

conductor or an insulator? Explain.

b. CALCULATE The specific heat of foam is about 1,200 J/(kg × K). How

much heat does it take to raise the temperature of 1 kg of foam

by 2 K?

I get it! Now I know that the way a material responds to heat depends on


147B

How Do Different Materials Respond to Heat?

Name Date Class

Thermal Properties On a separate sheet of paper, explain why when you have a metal lid stuck tightly on a glass jar, holding the sealed jar under a stream of hot water will often help loosen the lid. In your explanation, discuss heat conduction, specific heat, thermal energy, and thermal expansion.

147C

Name Date Class

Thermal Properties

1. Use your knowledge of insulators and conductors to explain why cooking pots are usually made of metal with some sort of plastic handle.

2. Listed are the specific heats of different substances, in J/(kg × K):

Air is 1,005; glass is 840; and silver is 233. Explain which of the three substances is the best insulator and why.

3. Five kilograms of Substance A requires 500 J of energy to raise its

temperature by 2 degrees. Five kilograms of Substance B requires 1,000 J of energy to raise its temperature by 2 degrees. How do the specific heats of the two substances compare?

4. Gold has a specific heat of 126 J/(kg × K). A sculptor increased the

temperature of a 0.5 kg block of gold by 10°C. How much energy did the sculptor add to the gold?

5. insulator 6. specific heat 7. thermal expansion 8. conductor

147D


Building Vocabulary On a separate sheet of paper, write a definition for each of these terms.

Name Date Class

Thermal Properties Thermostats A thermostat is a switch that is sensitive to changes in temperature. Thermostats are used to control the temperature of heating systems and cooling systems in homes, businesses, and vehicles. Thermostats also control the temperature of ovens, and turn on the fan of a computer when it becomes too warm.

A thermostat works on the principle of thermal expansion. When metals are heated, they expand, or become larger. Different metals expand at different rates. The amount of expansion depends on the length of the piece of metal and the temperature increase. For example, a one-meter length of steel expands 0.012 mm for every kelvin degree of temperature increase. A one-meter length of brass expands 0.019 mm for every kelvin degree of temperature increase.

A thermostat contains a bimetallic strip, a strip made of two metals, brass and steel, joined together. When the temperature increases, both metals expand. However, brass expands more than steel. Because the two pieces of metal are joined, the unequal expansion causes the strip to bend. The shorter steel is on the inside of the curve and the longer brass is on the outside of the curve.

In a heating system, when the room is cool, the bimetallic strip cools and contracts. As the strip straightens, it touches a contact in an electrical switch. This turns on the heating system. As the room warms, the bimetallic strip becomes warmer and expands. The strip curves and moves away from the contact. This turns off the heating system. Eventually, the room cools, and the strip straightens, starting the heating system again.

1. How could a bimetallic strip be used to make a thermometer? 2. Some thermostats have the bimetallic strip formed into a spiral. What

is the advantage of this shape? 3. A one-meter length of nickel expands 0.012 mm for every kelvin

degree of temperature increase. Why would a bimetallic strip made of nickel and steel not be a good choice for a thermostat?

147E

Read the passage. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Thermal Properties Fill in the blank to complete each statement.

1. A material with a(n) specific heat can absorb a great deal of thermal energy without a great change in temperature.

2. As the thermal energy of matter , its particles usually spread out.

3. If two objects of the same size require different amounts of heat to raise their temperatures 10 kelvin, the objects have different

4. To keep food warm or cool, coolers are made out of materials that are .

5. Water has a specific heat of 4,186 J/(kg × K). To raise the temperature of a bathtub of water (220 kg) by 3 kelvin, it takes Joules of energy.


6. Specific heat is measured in joules.

7. Most metals are good conductors of heat.

8. The amount of energy required to raise 1 kg of material by 1 kelvin is called thermal energy.

9. On a hot summer day, a metal door in a wood frame may stick and be hard to open due to specific heat.

10. Insulators do not conduct heat well.

147F

Name Date Class

Electric Charge and Static Electricity

I get it! Now I know that the way electric charges interact depends on


1a. DESCRIBE What happens to an object’s atoms when the object

becomes positively charged?

b. CHALLENGE Explain how you could use a piece of silk and a glass rod to attract a stream of tap water.

I get it! Now I know the four methods of building up static electricity are


165B

How Do Charges Interact?

How Does Charge Build Up?

Name Date Class


On a separate sheet of paper, explain how negative charges at the bottoms of storm clouds can cause lightning to strike earth.

165C

Name Date Class


1. Are the charges in the finger attracted or repelled by the charges in the doorknob? How can you tell?

2. What do the lines around the finger and doorknob represent? 3. One kind of static electricity is a result of electrons moving onto an

object from another object. What is another way static electricity can build up on an object?

4. force is the force between charged objects.

5. The buildup of charges on an object is called .

6. The law of of charges states that charges are not created or destroyed but transferred.

7. The transfer of charge from one object to another by rubbing is called .

8. The loss of static electricity as electric charges transfer from one object to another is called .

9. An electric is a region around a charged object where the object’s electric force is exerted on other charged objects.

10. When the electric field of one object causes a transfer of electrons from one part to another in a second object, without the two objects touching, it is called .

11. The transfer of charge when electrons move from a charged object to another object by direct contact is called .

165D

Understanding Main Ideas The person whose finger is shown below has walked across a carpet and is about to touch the doorknob. Answer the following questions on a separate sheet of paper.


Name Date Class

Electric Charge and Static Electricity St. Elmo’s Fire St. Elmo’s fire is a bluish glow sometimes seen during stormy weather on the tops of masts of ships, church steeples, and other tall pointed objects. Despite its name, St. Elmo’s fire is not a flame and does not burn the objects on which it appears. It is a type of static discharge, like lightning. St. Elmo’s fire can last for several minutes.

You know that electrons accumulate on the bottoms of clouds during thunderstorms and induce a positive charge in the ground. If enough charge builds up in this way, atoms in the air can be stripped of their electrons, producing a plasma. A plasma is a glowing gas with no net charge. It contains positive ions and free electrons. St Elmo’s fire is a plasma. The color of light given off by a plasma depends on the gas involved. The air in Earth’s atmosphere is mostly a mixture of oxygen and nitrogen gas. As a plasma, this mixture gives off a bluish glow.

1. An electric field tends to be strongest at the ends of pointed objects. How does this explain the fact that St. Elmo’s fire appears on pointed objects such as the masts of ships?

2. Compare and contrast St. Elmo’s fire with lightning. 3. The red glow of a neon light is also produced by a plasma. How

might the glow of the light change if the neon gas inside it were replaced by air?

4. Why does St. Elmo’s fire only occur during thunderstorms? 5. Based on what you have learned about lightning and St. Elmo’s fire,

do you think air is a good conductor of electric charge?

165E

Read the passage and look at the diagram below it. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Electric Charge and Static Electricity Write the letter of the correct answer on the line at the left.

1. Atoms contain charged particles called A protons, neutrons, and electrons B protons and electrons C protons and neutrons D electrons and neutrons

3. In static electricity, charges A flow continuously B flow intermittently C build up in an atom D build up on an object

2. A region around a charged object where the object’s electric force is exerted on other charged objects is an electric A field B outlet C socket D power plant

4. Charges can redistribute themselves

by friction, conduction, polarization, or A reduction B production C induction D superconduction


5. Charges that are different repel each other.

6. An electric field gets stronger the closer it is to the charge.

7. Charges do not transfer between objects in polarization or conduction.

8. Lightning is an example of static discharge.

9. Electric current is the buildup of charges on an object.

10. Most objects have some overall charge.

165F

Name Date Class

Electric Current 1a. REVIEW What is the unit of current?

b. PREDICT What could break the circuit between your home and an electric power plant?

I get it! Now I know that electric current is made of


I get it! Now I know that conductors and insulators are different because of


173B

How Is Electric Current Made?

How Do Conductors Differ From Insulators?

Name Date Class

Electric Current 2a. LIST List the four factors that determine the resistance of an object.

b. Battery A supplies 500 charges. Each charge has 2 J

of energy. Battery B supplies 50 charges, each of which has 4 J of energy. Which battery supplies more total energy? Which has a higher voltage?

I get it! Now I know that current is affected by


173C

What Affects Current Flow?

CHALLENGE

Name Date Class

Electric Current On a separate sheet of paper, write a paragraph using the terms electric current, voltage, resistance, ohm, ampere, and volt. Underline the terms.

173D

Name Date Class

Electric Current

1. When the wires are connected to the terminals of the battery, what causes electric current in the circuit?

2. What is the voltage source and what is the conductor in this circuit? 3. What are two ways you could alter the wire to increase the resistance

in the electric circuit?

4. electric current

5. insulator

6. voltage

7. resistance

8. conductor

9. electric circuit

a. the difference in electrical potential energy per charge between two points in a circuit

b. material through which charge can easily flow

c. a complete, unbroken path through which electric charges can flow

d. the continuous flow of electric charges through a material

e. the measure of how difficult it is for charges to flow through a material

f. material through which charge cannot easily flow

173E

Understanding Main Ideas Study the diagram below, then answer the following questions on a separate sheet of paper.


Name Date Class

Electric Current Surge Protectors A surge protector is a device used to protect computers and other electronic equipment from surges in current or voltage. An electric surge can be caused by a lightning strike on an electric line or when electronic devices that share a circuit are turned on or off. If you have computers in your classroom, they are probably plugged into a surge protector instead of directly into a wall outlet.

One way to protect electronic devices from high voltage is to use a varistor. A varistor is another name for a variable resistor. You have learned that a resistor is something in a circuit that resists current. A variable resistor, however, is designed to provide very low resistance at high voltage and very high resistance at low voltage. Thus, when a surge of electric current travels from the wall outlet to a surge protector, the resistance of the varistor suddenly decreases and current passes through the surge protector instead of through the computer (or other electronic device). At normal voltages, the resistance in the varistor remains high, and the current passes into the electronic device. The graph below shows how the current passing through a typical varistor changes with increasing voltage.

1. According to the graph, at about what voltage does current exist in the varistor?

2. Why do you think the graph shows a large, immediate increase in current after reaching a certain voltage, rather than a small, gradual current increase?

3. Suppose a surge protector had a very low resistance at all voltages. What do you think would happen?

4. Suppose a surge protector had a very high resistance at all voltages. What do you think would happen?

173F

Read the passage and look at the graph below it. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Electric Current Write the letter of the correct answer on the line at the left.

1. The unit for the rate of current is the A ampere B volt C ohm D joule

3. Potential electric current can be

converted into A heat B matter C waste D food

2. All electrical devices contain electric A acid B gears C circuits D motors

4. Which of the following does not

determine the resistance of a wire? A temperature B diameter C length D color


5. The amount of charge that passes through a wire in a given period of time is the rate of electric .

6. The electrons in conductors move about freely than the electrons in insulators.

7. Charges flow through wires because of differences in electric .

8. is the measure of how difficult it is for charges to flow through an object.

9. is the difference in electric potential energy per charge between two points in a circuit.

10. Current flow is affected by the of an object (such as the length of a wire) that the charge flows through.

173G

Name Date Class

Electric Circuits On a separate sheet of paper, make a Venn diagram that compares and contrasts a series and parallel circuit, each made up of a battery, wires, and light bulbs.

181C

Name Date Class

Electric Circuits

1. Which circuit is a series circuit?

2. Which circuit is a parallel circuit?

3. If bulb A goes out, what happens to the light in the other two bulbs in that circuit?

4. If bulb B goes out, what happens to the light in the other two bulbs in that circuit?

5. If a fourth bulb is added similar to the existing bulbs in Circuit 1, what happens to the resistance in the circuit?

6. If a fourth bulb is added similar to the existing bulbs in Circuit 2, what happens to the resistance in the circuit?

7. How many paths can current take in Circuit 1?

8. How many paths can current take in Circuit 2?

9. In a(n) circuit, all parts are connected one after another along one path.

10. says that resistance is equal to the voltage divided by the current.

11. In a(n) circuit, the different parts of the circuit are on separate branches.

181D

Understanding Main Ideas Each of the circuit diagrams below shows a battery and three light bulbs. Study the circuits and then answer the questions in the spaces provided.


Circuit 1 Circuit 2

Name Date Class

Electric Circuits Electrical Energy Outages An electrical energy outage is the loss of electric current to a home, business, neighborhood, or even an entire city. Electric current is fed into homes and businesses with heavy-duty wires called lines. Feeder lines deliver current to several thousand homes and businesses. Primary lines branch off of feeder lines and deliver current to between five and thirty buildings. Finally, individual lines to homes and businesses branch off of primary lines.

An electrical energy outage can occur when any of these lines is damaged or broken. The diagram below shows a simplified version of three electrical energy outages due to fallen trees. To repair the circuit, workers would first repair the feeder lines. This would restore electric current to houses 2 and 3. Next, the primary line would be repaired, restoring current to houses 4 and 5. Finally, the individual line to house 1 would be prepared.

1. If the primary line had been repaired first, would electric current have been restored to houses 4 and 5? Explain.

2. Suppose that a week later the current in house 4 goes out, but the current in house 5 stays on. Where should a repair worker look for a damaged line?

3. The next week, the electric current in both houses 2 and 3 goes out, but it stays on in houses 1, 4, and 5. Where should a repair worker look for a damaged line?

4. Suppose that houses 1 through 5 were connected by a series circuit. What would happen if one of the lines in the circuit was damaged?

181E

Read the passage and look at the diagram within it. Then use a separate sheet of paper to answer the questions that follow the passage.

Name Date Class

Electric Circuits Write the letter of the correct answer on the line at the left.

1. When more branches are added to a parallel circuit, A resistance increases B the current has more paths to follow C resistance decreases D the current has fewer paths to follow

3. The path of current in a circuit is

completed by A a transformer B an energy source C conducting wires D an electrical device

2. Batteries and power plants are examples of A energy sources B energy conduction C energy transformation D energy conservation

4. Resistance in a circuit is equal to

voltage divided by A joules B current C power D amperage


5. Electrical energy in a circuit gets transformed into other forms of energy, such as mechanical energy.

6. Isaac Newton formulated Ohm’s law.

7. Opening a switch breaks an electric device.

8. All electric circuits have the same basic features.

9. Energy is always lost in a circuit.

10. Most conductors have a(n) inconstant resistance regardless of the applied voltage.

181F

Name Date Class

Electric Power and Safety 1a. REVIEW The power of an appliance can be found by multiplying

by .

b. CALCULATE How much energy does an 850 W toaster consume if it is used for 1.5 hours over the course of a month?

I get it! Now I know that electric power and energy depend on


I get it! Now I know that electric safety devices


185B

How Do You Calculate Electric Power and Safety?

How Can Electric Shocks Be Prevented?

Name Date Class

Electric Power and Safety

On a separate sheet of paper, explain how to calculate power. Then write a paragraph explaining how shocks can be prevented.

185C

Name Date Class

Electric Power and Safety

1. What is the equation used to calculate power?

2. What is the equation used to calculate the total amount of energy used by an appliance?

3. Why is it important for people to avoid electric shocks?

4. A circuit is when charges are able to flow directly from the circuit into Earth.

5. A(n) is a device in a circuit that melts if there is too much current in it.

6. The of an electrical plug connects the metal parts of appliances to the ground wire of a building.

7. A(n) is a connection that allows current to take the path of least resistance.

8. A(n) is a switch that stops the flow of current in a circuit if the circuit gets too hot.

185D

Understanding Main Ideas Answer the following questions in the spaces provided. Use a separate sheet of paper if you need more room.


Name Date Class

Electric Power and Safety James Watt and Horsepower James Watt was a Scottish engineer who invented a practical and efficient steam engine in the late 1700s. To tell people about how powerful his steam engine was, Watt decided to compare it to the power of the horses that were used to do heavy work at the time. Watt observed horses at a local mine using a rope to lift buckets of coal up from the mine at a rate of 220 pounds of coal 100 feet in 1 minute, or 22,000 foot-pounds of work in 1 minute. To overestimate, the horses’ work, he increased that number to 33,000 foot-pounds of work in 1 minute. That unit of measurement he called “1 horsepower.” The unit of horsepower (hp) is still used today in the United States when referring to the power of engines.

In honor of the work of James Watt, the metric unit of power was named the watt. Watts (W) or kilowatts (kW) are used when referring to the power of electric devices. You can convert horsepower to watts by using this equation: 1 hp = 746 W.

1. What is 1 horsepower equal to in the metric system? 2. A lawnmower is advertised as having 1.5 horsepower. What is the

lawnmower’s power rating in watts? 3. Suppose the unit horsepower actually replaced watt as the unit of

power for electric appliances. What would the power rating of a 500-W refrigerator be in horsepower?

185E

Read the passage and look at the diagram above it. Then use a separate sheet of paper to answer the questions that follow the passage.

Name Date Class

Electric Power and Safety Write the letter of the correct answer on the line at the left.

1. The power of a light bulb or appliance depends on A kilowatts and hours B voltage and current C fuses and circuit breakers D transformation of energy

3. The amount of current running

through a clock radio that uses a standard wall outlet (120 volts) and has a power rating of 12 watts is A 0.1 amps B 1.0 amps C 10 amps D 100 amps

2. The unit of power is the A watt B volt C ampere D kilowatt

4. An electric bill charges for the month’s A wattage B amperage C energy use D voltage


5. You can calculate current by multiplying power by voltage.

6. Electric power is usually measured in watts.

7. The equation Energy = Power × Current can be used to find the amount of energy used by an appliance.

8. A short circuit allows current to take the path of greatest resistance.

9. Fuses and circuit gauges prevent circuits in a home from overheating.

10. A circuit connected to Earth with a three-pronged plug is resistant.

185F

Name Date Class

What Is Magnetism?

I get it! Now I know that three properties of magnets are that magnets


1a. IDENTIFY What area of a magnet has the strongest magnetic effect?

b. RELATE CAUSE AND EFFECT How can two magnets demonstrate force?

I get it! Now I know that magnetic poles that are unlike

and magnetic poles that are alike


199B

What Are the Properties of Magnets?

How Do Magnetic Poles Interact?

Name Date Class

What Is Magnetism?

On a separate sheet of paper, list three properties of magnets and explain how magnetic poles interact.

199C

Name Date Class

What Is Magnetism?

1. Are these magnets attracting or repelling each other? How can you tell?

2. What would happen if the magnet on the left were turned around,

so that its north pole faced the north pole of the other magnet?

3. Any magnet has two ends, each one called a(n) .

4. A(n) is any material that attracts iron and materials that contain iron.

5. The attraction or repulsion between magnetic poles is .

6. is the attraction or repulsion of magnetic materials.

199D

Understanding Main Ideas The diagram below shows two magnets. Use the diagram to answer the questions below in the spaces provided.


Name Date Class

What Is Magnetism? William Gilbert and the Science of Magnetism Sir William Gilbert lived in England in the 1500s. He is remembered today for his investigations into electricity and magnetism. In fact, he is sometimes credited with founding the science of magnetism. He published descriptions of his many investigations in a book called De Magnete or “On the Magnet.” In this book, he described carrying out many investigations using lodestone in the shape of a sphere, or “little Earth.” Through his experiments, Gilbert became the first person to describe magnetic attraction in terms very similar to the way modern scientists describe a magnetic field.

Gilbert was the first to use the terms magnetic pole and magnetic force. He showed through experimentation that a magnet exerts a force through a distance—a force that does not involve touching. He showed that the strength of a magnet could be increased if pieces of soft iron were added at the magnet’s poles. He also showed if an iron magnet is red hot, the magnet loses its magnetism. Another notion he advanced was that Earth itself is a giant magnet. This is an idea that modern scientists know to be true.

1. Who was William Gilbert, and when did he live? 2. What book did he publish on magnetism? 3. What did Gilbert show about magnetic force? 4. What did he prove about magnets and heat? 5. What notion about Earth did he advance that has proven true?

199E

Read the passage. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

What Is Magnetism? Write the letter of the correct answer on the line at the left.

1. Two south magnetic poles brought near each other A repel each other B attract each other C cancel each other D magnetize each other

3. Two north magnetic poles brought

near each other A magnetize each other B attract each other C cancel each other D repel each other

2. A north magnetic pole brought near a south magnetic pole A nullifies the south pole B attracts the south pole C repels the south pole D magnetizes the south pole

4. A south magnetic pole brought near

a north magnetic pole A repels the north pole B attracts the north pole C nullifies the north pole D magnetizes the north pole


5. Any material that exerts magnetic force is considered a magnet.

6. Like all other forces, a magnetic force is a(n) gravitational force.

7. The area between the poles of a magnet has the strongest effect.

8. Magnets attract wood and materials that contain iron.

9. When freely swinging, one end of a magnet always points east.

10. Magnets have the same properties as sedimentary rocks.

199F

Name Date Class

Magnetic Fields 1a. DEFINE What is a magnetic field?

b. DESCRIBE Describe the magnetic field of a south-south pole arrangement.

I get it! Now I know that a magnetic field’s shape is


I get it! Now I know that Earth has a magnetic field


205B

What Is a Magnetic Field’s Shape?

What Is Earth’s Magnetic Field Like?

Name Date Class

Magnetic Fields On a separate sheet of paper, explain how Earth is like a magnet.

205C

Name Date Class

Magnetic Fields

1. In what ways are Earth and a bar magnet alike?

2. If you follow a compass pointing north, will you reach the geographic

north pole? Explain your answer.

3. Draw a magnetic field around the illustration of the bar magnet

shown here.

4. magnetic field

5. declination

6. magnetic field lines

7. compass

a. navigation device whose magnetized needle usually points north

b. map the invisible field around a magnet

c. angle between geographic north and the north to which a compass needle points

d. area of magnetic force around a magnet

205D



Name Date Class

Magnetic Fields Magnetic Properties of Elements Ferromagnetic materials are made up of regions known as domains. Within each domain, the magnetic fields of all the atoms are lined up in the same direction. When exposed to a magnetic field, the domains tend to line up with the field. Due to the existence of domains, ferromagnetic materials are easily magnetized. Their ease of magnetization is represented by a large whole number. (This number is a ratio. It has no units.)

Paramagnetic materials do not have magnetic domains, and their atoms tend to line up individually with a magnetic field. For this reason, paramagnetic materials are much more difficult to magnetize than ferromagnetic materials. Their ease of magnetization is represented by very small numbers.

Diamagnetic materials have no magnetic domains. Therefore, their atoms do not easily align with a magnetic field. Their ease of magnetization is represented by very small numbers. However, they are different from paramagnetic materials because their atoms align in a direction opposite to the magnetic field.

Material Ease of Magnetization

Iron approx. 1,000

Silver −20 millionths

Cobalt approx. 170

Magnesium 13 millionths

Aluminum 17 millionths

Chromium 180 millionths

Nickel approx. 80

Gold −28 millionths

1. Which materials are ferromagnetic? Explain. 2. Which materials are paramagnetic? Explain. 3. Which materials are diamagnetic? Explain.

205E

The table below shows the ease of magnetization for several materials. Read the passage and study the table. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Magnetic Fields Fill in the blank to complete each statement.

1. A(n) is a device that has a magnetized needle that can spin freely.

2. is the angle between geographic north and the north to which a compass needle points.

3. When the magnetic fields of two or more magnets overlap, a(n) magnetic field forms.

4. Magnetic field lines are closest together at the .

5. The motion of liquid in Earth’s outer core creates a magnetic field.

6. A compass behaves as it does because each needle acts as a(n) . If the statement is true, write true. If the statement is false, change the underlined word or words to make the statement true.

7. Earth’s magnetic poles are not in the same place as the geographic poles.

8. Magnets cannot interact without touching.

9. Magnetic field lines always cross.

10. The effects of a magnetic field can be observed using non-metal filings.

205F

Name Date Class

Electromagnetic Force 1a. EXPLAIN What did Oersted conclude?

b. RELATED CAUSE AND EFFECT How does a current affect a compass?

I get it! Now I know that an electric current produces a


I get it! Now I know that the magnetic field produced by a current can be changed

by


211B

How Are Electric Currents and Magnetic Fields Related?

What Is a Magnetic Field Produced By a Current Like?

Name Date Class

Electromagnetic Force 2a. DEFINE What is a solenoid?

b. APPLY CONCEPTS What are four ways to make an electromagnet stronger?

I get it! Now I know that both solenoids and electromagnets


211C

What Are the Characteristics of Solenoids and Electromagnets?

Name Date Class

Electromagnetic Force On a separate sheet of paper, compare solenoids and electromagnets.

211D

Name Date Class

Electromagnetic Force

1. What kind of magnets are shown in the figure above?

2. Assuming the batteries are the same, which magnet do you think is stronger, A or B? Explain your answer.

3. List four factors that can be varied to change the strength of the magnets.

4. electromagnetism

5. solenoid

6. electromagnet

a. a solenoid with a ferromagnetic core

b. the relationship between electricity and magnetism

c. a coil of wire with a current

211E

Understanding Main Ideas Use the illustration below to answer Questions 1–3.


Name Date Class

Electromagnetic Force

A Turn for the Better There are many ways to increase or decrease the strength of an electromagnet. Two of these involve electric current and the coils of a solenoid. How are these factors related to each other, and what is the total effect produced by varying them? The unit used to determine the result of this relationship is the ampere-turn. The ampere-turn is a measure of the strength of an electromagnet. An ampere, or simply an amp, is a unit of electric current.

The table below shows the results of varying the number of turns of a wire around a solenoid and the current through that wire. All other factors stay the same. For Items 1 and 2, fill in the blanks in the table with the correct value.

3. What is the relationship in the above table between current and turns as they relate to the strength of an electromagnet?

4. There are 200 turns of wire around an electromagnet. The current in the wire is 6 amp. You want to increase the strength of the magnet to 1.5 times its present strength. What are two changes you can make to achieve your goal? Show all your calculations.

5. The current leading into an electromagnet with a strength of 800 ampere-turn is reduced by the electric company from 20 amp to 10 amp. What can you do to keep the strength of the electromagnet constant? Show all your calculations.

211F

Current (amp) Turns Electromagnetic Strength (ampere turn)

2 125 250

5 125 625

12 100 1,200

12 200 2,400

14 250 1. 2. 300 4,800

Read the passage and study the table. Then complete the table and use a separate sheet of paper to answer the questions that follow.

Name Date Class

Electromagnetic Force Write the letter of the correct answer on the line at the left.

1. You can increase the strength of an electromagnet by A changing the position of the compass B adjusting the magnetic declination C using a stronger ferromagnetic material for

the core D reversing the magnetic domains

3. The north and south poles of a

solenoid change with A the type of material in the core B the number of loops in the coil C the tightness of loops in the coil D the direction of the current

2. You can increase the strength of an electromagnet by A adding loops of wire B decreasing the current in the solenoid C winding the coils more loosely D using direct current

4. Both solenoids and electromagnets produce magnetic fields using A electric current and coiled wires B compasses and magnetic fields C coiled wires and a ferromagnetic core D electric current and a battery


5. discovered that wherever there is electricity, there is magnetism.

6. An electric produces a magnetic field.

7. There are ways to change the strength of a magnetic field.

8. You can increase the strength of a magnetic field by increasing the amount of in the wire.

9. To change the direction of a magnetic field, you reverse the direction of the .

10. are used in electric motors, earphones, and in junkyards to lift old cars and other heavy steel objects.

211G

Name Date Class

Electricity, Magnetism, and Motion

I get it! Now I know that when a wire with a current is placed in a magnetic field, electrical

energy


1a. REVIEW What does a galvanometer measure?

b. RELATE CAUSE AND EFFECT What causes the pointer to move in a galvanometer?

I get it! Now I know that a galvanometer works by using


217B

How Is Electrical Energy Transformed Into Mechanical Energy?

How Does a Galvanometer Work?

Name Date Class

Electricity, Magnetism, and Motion 2a. DEFINE What is an electric motor?

b. SUMMARIZE What makes the armature turn continuously?

I get it! Now I know that an electric motor transforms


217C

What Does an Electric Motor Do?

Name Date Class

Electricity, Magnetism, and Motion

On a separate sheet of paper, explain what galvanometers and electric motors do and identify one characteristic they share.

217D

Name Date Class

Electricity, Magnetism, and Motion a. transforms electrical energy to mechanical energy b. contains a loop of wire with a current in a magnetic field c. rotates only half a turn d. rotates continuously e. turns an axle f. turns a pointer on a scale g. current is reversed h. current is not reversed

4. A device that uses electric current to turn the blades of a blender is an example of a(n) .

5. A moving fan blade has a type of energy called .

6. Electric current can be measured with a device called a(n) .

7. is the ability to move an object some distance.

8. An electric motor turns an axle by transforming into mechanical energy.

217E

Galvanometer Electric Motor

1. 2. 3.

Understanding Main Ideas For Questions 1–3, write the letter of each characteristic in the correct area of the Venn diagram.


Name Date Class

Electricity, Magnetism, and Motion Where’s the Action? Although you probably cannot see most of them, you are surrounded by electric motors. They are found in such products as vacuum cleaners, electric drills, elevators, washing machines, air conditioners, factory robots, and huge railroad locomotives. Electric motors help warm and cool your home and keep industries humming.

As you can tell from the list above, the devices vary greatly in size. So do their functions. But whether large of small, whether cleaning or cooling, their actions are controlled by the same thing, the electric motor.

1. What part of the hair dryer does the motor move? 2. Describe what happens as the hair dryer takes in cool air from one

end and blows out warm air from the other. 3. Which of the appliances listed in the first paragraph above is most

like a hair dryer? Explain your answer. 4. Suggest how an electric motor can help keep a home warm.

217F

The diagram below shows a hair dryer where the electric motor is the key part. Read the passage and study the figure. Then use a separate sheet of paper to answer the questions that follow.

Name Date Class

Electricity, Magnetism, and Motion Write the letter of the correct answer on the line at the left.

1. The energy an object has due to its movement or position is called A static energy B mechanical energy C excess energy D potential energy

3. When a wire with a current is placed

in a magnetic field, A kinetic energy is transformed into potential

energy B electrical energy is transformed into sound

and light C electrical energy is transformed into

mechanical energy D solar energy is transformed into light and

heat

2. The energy associated with currents is called A mechanical energy B magnetism C geothermal energy D electrical energy

4. An electric motor uses an electric

current to turn a(n) A pointer B brush C axle D wheel


5. A galvanometer measures small objects.

6. An electric motor transforms matter.

7. An electric current is used to turn the numbers of a galvanometer.

8. The armature of an electric motor rotates occasionally when the current is turned on.

9. Permanent magnets produce an electric field that causes the armature of an electric motor to turn.

10. Current always flows from the positive to negative terminals of a battery.

217G

Name Date Class

Electricity From Magnetism 1a. DESCRIBE What is one way to induce an electric current?

b. CLASSIFY Give an example of an electronic appliance that runs on AC and one that runs on DC.

I get it! Now I know that electric current is induced when


2a. REVIEW What is one way to induce an electric current?

b. ANSWER How are electricity and magnetism related?

I get it! Now I know an electric current is induced when


225B

How Can an Electric Current Be Produced in a Conductor?

How Does a Generator Work?

Name Date Class

Electricity From Magnetism 3a. IDENTIFY Which coil has more loops in a step-down transformer?

b. INFER Why do some appliances have step-down transformers built in?

I get it! Now I know a transformer is a device used to


225C

What Does a Transformer Do?

Name Date Class

Electricity From Magnetism On a separate sheet of paper, define electromagnetic induction and give an example.

225D

Name Date Class

Electricity From Magnetism

1. As a generator crank is turned, the rotates in the magnetic

field.

2. The up-and-down motion of the armature induces a(n) in the wire.

3. After the armature turns halfway, each side of it direction in the magnetic field.

4. The result is that a(n) electric current is induced.

5. electromagnetic induction

6. alternating current

7. direct current

8. electric generator

9. transformer

a. device that increases or decreases voltage

b. generating a current from the motion of a conductor through a magnetic field

c. type of current found in the circuits of homes

d. type of current produced by a battery

e. device that transforms mechanical energy into electrical energy

225E

Understanding Main Ideas Fill in the blank to complete each statement about generators.


Name Date Class

Electricity From Magnetism Stepping Up and Down You can determine the characteristics of a transformer and discover whether it is a step-up or a step- down transformer, how many wire turns there are in either the primary or secondary coil, and what the voltage is in either of the coils. To find the voltage in the secondary coil of a transformer, you need to use the following equation:

=up s

sp

V NVN

Vp equals the voltage in the primary coil, Vs equals the voltage in the secondary coil, Ns equals the number of wire turns in the secondary coil, and Np equals the number of wire turns in the primary coil.

To find the voltage in the secondary coil in A below, multiply the number of wire turns in the secondary coil by the voltage in the primary coil. Divide the result by the number of wire turns in the primary coil.

120 8 turns= (240 )4 turns

uVV

The number of wire turns can also be calculated using another form of the equation. To calculate the number of wire turns in the secondary coil, use the following equation:

=up s

sp

N VNV

1. Drawing B: What is the number of wire turns in the primary coil? Secondary coil?

2. Drawing B: What is the voltage in the secondary coil? 3. Is the transformer in drawing a step-up or step-down transformer? 4. Drawing C: How many wire turns are in the primary coil? 5. Drawing C: How many wire turns are in the secondary coil?

225F

Read the passage and study the drawings below. Then use the drawings and a separate sheet of paper to answer the questions that follow.

Name Date Class

Electricity From Magnetism Write the letter of the correct answer on the line at the left.

1. A device that increases voltage is a(n) A step-down transformer B step-up transformer C magnetic transformer D electric transformer

3. An electric motor uses

A visible light to produce mechanical energy B mechanical energy to produce sound C mechanical energy to produce electricity D electrical energy to produce mechanical

energy

2. A device that decreases voltage is a(n) A step-up transformer B step-down transformer C magnetic transformer D electric transformer

4. An electric generator transforms

A mechanical energy into electrical energy B mechanical energy to sound C electrical energy to mechanical energy D electromagnetic energy to mechanical

energy


5. As the crank of a generator is turned, the slip ring rotates in the magnetic field.

6. In a generator, the up-and-down motion of the crank induces a current in the wire.

7. The voltage in the primary coil of a transformer induces a current in the secondary coil.

8. An electric current is produced in a conductor when the conductor moves through a generator.

9. A current that constantly reverses is called direct current.

10. A(n) DC voltage can easily be raised or lowered.

225G

describing motion - mr. regan's educational...

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