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Newton’s 2nd Law Unit Student Design Cover Page(See directions on page 19)

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Newton’s 2nd Law Unit Front Page

At the end of this unit I will be able to:q Apply Newton’s second law to conceptual scenarios to predict changes in acceleration,

mass, or force. q Define terminal velocity and relate it to Newton’s second law. q Describe how and why acceleration occurs. q Sketch free body diagrams and calculate net force, acceleration, and/or mass.

Roots, prefixes, and suffixes I will understand and recognize are:q Kilo-, equ-, -gram, in-, term-, -tion

The terms I will clearly define are:q Acceleration, air resistance, directly proportional, force, free-body diagram, friction,

inversely proportional, mass, net force, Newton, pascal, pressure, terminal velocity

The assignments I will have completed by the end of the unit are:q Newton’s 2nd Law Notes and Review (page 160-162)q Force & Acceleration Guided Practice (page 163-164)q Newton’s 2nd Law Worksheet (page 165-166)q Free Body Diagram Practice (page 167)q Two-Force Problems (page 168)q Newton’s 2nd Law Puzzle (page 169)q Force Predictions Worksheet (page 171)q Friction & Other Force Notes and Review (page 172-174)q Friction Guided Practice (page 175-177)q Friction Worksheet (page 178-179)q Force and Mass Lab (page 180-182)q Newton’s 2nd Law Study Guide (page 183-186)q Newton’s 2nd Law Concept Map (page 187)q

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Vocabulary Predictions

Vocabulary term My definition Textbook definition

Acceleration

Air resistance

Force

Free-body diagram

Mass

Pressure

Terminal speed/velocity

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Newton’s 2nd Law Review

1. If you triple the net force acting on an object, what will happen to its acceleration?

2. If you take away half of an object’s mass, how much force is required to keep it accelerating at the same rate?

3. If you want an object to accelerate at four times its current rate, what are the two ways you could accomplish this task?

4. What is acceleration?

5. How is acceleration produced?

6. What is the “net force”?

7. Rewrite Newton’s 2nd law in your own words below:

8. Rewrite Netwon’s 2nd law as an equation below:

9. Rearrange the formula above to solve for “a”:

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10. Rearrange the formula above to solve for “m”:

Notes Summary:

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Newton’s 2nd Law Notes

What is acceleration? Acceleration is the rate at which ____________________________ changes.

How are acceleration, velocity, and force related?

__________________________________________ = _________________________________________= _______________________________________________________

How are acceleration, mass, and force related to each other?

_________________________________ causes ________________________________. ______________________________ is directly proportional to

______________________________________. Acceleration is ________________________ proportional to ________________.

_____________ = __________________

What is Newton’s Second law?

The __________________________________ produced by a _____________________ _____________________on an object is __________________________________ proportional to the magnitude of the _________________ ____________________, is in the same __________________________________ as the net force, and is inversely proportional to the __________________________________ of the object.

(or)

_____________ = __________________

How are force and acceleration related?

Newton’s second law states that force is _____________________________ ___________________________________to acceleration (when mass is constant).

What will happen if we double the force on an object?If you double the net force on an object, _______________________________________________________________________________________________________________________________

How are force and mass related?

Newton’s second law states that force is _____________________________ ___________________________________ to mass (when acceleration is constant).

What will happen if we double the mass on an object?If you double the mass of an object, ____________________________________________________________________________________________________________________________________

How are mass and acceleration related?

Newton’s second law states that acceleration is _____________________________ ___________________________________ to mass (when the force is constant).

What would happen to the acceleration of an object if we doubled the mass?If you double the mass of an object, ______________________________________________

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_______________________________________________________________________________________

Force & Acceleration Guided Practice

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Force & Acceleration Guided Practice

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Newton’s 2nd Law Worksheet

1. A water skier has a mass of 79 kg and accelerates at 1.4 m/s2. What is the net force acting on him?

2. What is the mass of an object if it takes a net force of 32 N to accelerate it at a rate of 0.88 m/s2?

3. A net force of 15 N is applied to a cart with a mass of 2.1 kg.a. What is the acceleration of the cart?b. How long will it take the cart to travel 2.8 m, starting from rest?

4. What is the acceleration of a box weighing 666 N if a force of 777 N is applied to it?

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Newton’s 2nd Law Worksheet

5. A car has a mass of 820 kg. It starts from rest and travels 41 m in 3.0 s. What is the net force applied to the car?

6. What is the net force needed to lift a full grocery sack (weighing 210 N) uniformly? What is the net force needed to accelerate the grocery sack upward at 1.5 m/s2?

7. What will be the final velocity of a 5.0 g bullet starting from rest, if a net force of 45 N is applied over a distance of 0.80 m?

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Free Body Diagram Practice

Construct free-body diagrams for the following situations. Label all forces (W, T, Fn, Fapp, Ff, Fair, etc)1. A physics book rests upon a level table.

2. A large crate is being pushed leftward at a constant velocity.

3. The brakes are applied to a car moving to the right, and it skids to a stop.

4. A spider is slowly descending a thin silk thread at a constant speed.

5. A projectile is moving upwards and rightwards toward the peak of its trajectory.

6. A force is applied to accelerate a crate across a rough horizontal surface.

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Two-Force Problems

1. A box with a weight of 22 N falls through the air with a wind resistance of 14 N. a. Draw a diagram showing both forces acting on the box.

b. What is the net force acting on the box?

c. Calculate the mass of the box.

d. Use Newton’s 2nd law to calculate the acceleration of the box.

2. A bucket of water weighing 110 N is being lifted by a person pulling upward on a rope with a force of 130 N.

a. Draw a diagram of the two forces acting on the bucket.

b. What is the net force on the bucket?

c. Calculate the mass of the bucket.

d. Use Newton’s 2nd law to calculate the acceleration of the bucket.

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Newton’s 2nd Law Puzzle

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Force Predictions Worksheet

The diagrams below show situations in which forces are acting on objects. Study each diagram. Then, answer the questions.

1. In which diagram are the forces balanced? 2. What will happen to the object in each diagram? Why?

3. What factor is different in diagrams A & B? What factor is the same?

4. Which object will have the greater acceleration? Why?

5. How do diagrams A & B compare?

6. Which object will have the greater acceleration? Why?

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7. What factors are different in diagrams A & B?

8. Which object will have the greater acceleration? Why?

Friction & Other Force Review

1. What is the cause of friction?

2. What direction does friction act?

3. The force of friction acting on a sliding crate is 100 N.a. How much force must be applied to maintain a constant velocity?

b. What will be the net force acting on the crate?

c. What will be the acceleration?

4. What is the difference between force and pressure?

5. Which produces more pressure on the ground, a person standing up or the same person lying down?

6. The force of gravity is twice as great on a 2-kg rock as on a 1-kg rock. Why does the 2-kg rock not fall with twice the acceleration?

7. How much air resistance acts on a 100-N bag of nails that falls at its terminal speed?

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8. How do air resistance and weight compare when an object is at terminal speed?

9. All other things being equal, why does a heavy sky diver have a terminal speed greater than a light sky diver? What can be done so that the terminal speeds are equal?

10.a. What is the net force acting on a 25-N freely falling object?

b. What is the net force when the object encounters 15 N of air resistance?

c. When it falls fast enough to encounter 25 N of air resistance?

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Friction & Other Force Notes

What is friction?

Remember, friction is a force that: ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________

___________________________________________________________________________

Where else can friction occur?

Friction can also occur in ___________________________ and ___________________________ (both called ___________________________).

______________________________________________________is a type of fluid friction.

What is pressure?

Pressure is _____________________________________________________________________

Units for force are ___________________________ per square _____________________, which are called ______________________________ (Pa).

What is terminal speed or terminal velocity?

Air resistance ___________________________________ as an object gains speed.

At a certain speed, called terminal speed, ________________________________________________________________________________________________________________________

Terminal speed is where ________________________________________________is equal to ___________________________.

When weight is pulling down with the same force that air resistance is pushing up, the _________________________________________________________________.

Zero net force means ___________________________________________________________.

So what happens to the falling object?________________________________________________________________________________________________________________________________________________________________________

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How does weight relate to Newton’s 2nd law?

Weight is ____________________________ and an example of F=ma.

“a” for weight, is “g” – ________________________________________________ g ~ __________________ m/s2 for all objects. This means that the ratio F/m is the same for all objects and

explains why ______________________________________________________________________________________________________________________________________

Friction Guided Practice

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Friction Guided Practice

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Friction Worksheet

1. A force of 42 N is needed to start a box sliding across the floor. The weight of the box is 55 N. Draw all the forces acting on the box.

a. How large is the force of friction?

b. Is the frictional force static or kinetic?

c. What is the coefficient of friction?

2. If the coefficient of kinetic friction between a crate and the floor is 0.20, how much force is needed to slide a 92 kg crate uniformly across the floor?

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Friction Worksheet

3. A hockey puck has a mass of 1.0 kg. The coefficient of kinetic friction between the puck and ice is 0.15. A force of 2.6 N is applied horizontally to the puck to push it to the right. Draw and label all the forces acting on the puck.

a. The normal force acting on the puck is _______ N.

b. The force of kinetic friction is ______N.

c. The net force acting on the puck horizontally is _________N.

d. The acceleration of the puck will be _________m/s2.

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Force and Mass Lab Flow Chart(to be completed together in class)

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Force and Mass Lab Data Sheet(Rough Draft Version. Neatly type/rewrite into your lab report)

Trial

Force on Cart

Mass on Cart Distance Time (s) Speed (m/s)

1 5 N .2 kg 0.5 m2 5 N .2 kg 0.5 m3 5 N .2 kg 0.5 m

Avg =

Trial

Force on Cart

Mass on Cart Distance Time (s) Speed (m/s)

1 5 N .4 kg 0.5 m2 5 N .4 kg 0.5 m3 5 N .4 kg 0.5 m

Avg =

Trial

Force on Cart

Mass on Cart Distance Time (s) Speed (m/s)

1 5 N .5 kg 0.5 m2 5 N .5 kg 0.5 m3 5 N .5 kg 0.5 m

Avg =

Trial

Force on Cart

Mass on Cart Distance Time (s) Speed (m/s)

1 5 N 1 kg 0.5 m2 5 N 1 kg 0.5 m3 5 N 1 kg 0.5 m

Avg =

Mass on Cart

Average Speed

.2 kg

.4 kg

.5 kg1 kg

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Force and Mass Lab Graph & Conclusion Questions(Rough Draft Version. Neatly type/rewrite into your lab report)

Create a line graph of the effect of mass on the average speed of the cart.

x-axis = y-axis =

.2 kg .4 kg .5 kg 1 kg

Effect of Mass on Average Speed

spee

d (m

/s)

Conclusion Questions:*** Answer the questions below but also discuss them in your lab report!

1. Is the slope of the line graph above a positive or negative slope?

2. As the mass of the cart increases, the speed of the cart

3. The relationship between these variables is inversely or directly proportional?

4. What was the independent variable in this lab?

5. What was the dependent variable in this lab?

6. List three constants in this investigation.

1.

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2.

3.

Newton’s 2nd Law Study Guide

1. What causes acceleration? 2. A 5-kg object experiences a net force of 10 N. What is the acceleration?

3. A 5-kg object is accelerating at 7 m/s2. What net force must be acting on the object?

4. An object with an unknown mass is moving at 3 m/s2 because of a 2 N force. What is the mass of the object?

5. Which has more air resistance: an elephant or a feather. Explain why.

6. Define terminal velocity. Include the following words: net force, weight, opposite, zero, falling

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7. A 15-kg crate is pulled leftwards across the floor. Draw a free body diagram that includes the following forces:

- Weight- Normal force- Friction force- Applied force

Newton’s 2nd Law Study Guide

8. If the crate in problem #7 is not accelerating, what does that tell us about the applied force and the friction force?

9. A force of 5 N is applied over an area of 0.3 m2. What is the pressure in pascals?

10. Why will a heavy tractor sink less deeply in mud than a horse’s hooves or a person’s foot?

11. Liz pulls her sister in a red wagon at a constant speed with a force of 200 N. What is the net force on the wagon? What is the force of friction on the wagon?

12. A skydiver jumps from a high altitude balloon. a. As she calls faster and faster though the air, does air resistance increase,

decrease, or stay the same? b. Does the net force on her increase, decrease, or stay the same?

c. Does her acceleration increase, decrease, or stay the same?

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13. Felicia, the ballet dancer, has a mass of 45.0 kg. a. What is Felicia’s weight on earth?

b. What is Felicia’s mass on Jupiter, where acceleration due to gravity is 25.0 m/s2?

c. What is her weight on Jupiter?

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Newton’s 2nd Law Study Guide

14. A 20-g sparrow flying toward a bird feeder mistakes a glass window for an opening and slams into it with a force of 2.0 N. What is the bird’s acceleration?

15. Brook comes home from school and puts his books down on the kitchen table while he grabs a snack. The book have a combined weight of 25 N and the area of contact with the table is 0.2m by 0.3 m. What pressure do the books apply to the table?

16. Complete the chart below:

Unit?

Weight

Mass

Force

Acceleration due to gravity

Velocity

Pressure

Air resistance

Friction

Acceleration

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Newton’s 2nd Law Unit Concept Map(see page 19 for directions)

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Newton’s 2nd Law Unit Concept Cards

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Newton’s 2nd Law Unit Back Page

The California Dept. of Education Standards I have come to understand are:

q 1. Newton’s laws predict the motion of most objects. As a basis for understanding this concept:

q a. Students know how to solve problems that involve constant speed and average speed.

q b. Students know that when forces are balanced, no acceleration occurs; thus an object continues to move at a constant speed or stays at rest (Newton’s first law).

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