On-level Physics – Second Quarter

Monday Tuesday Wednesday Thursday Friday October 15 16 17 18 19

No school Go over quiz Friction

TEST: Projectiles, Newton’s laws, Forces, Friction

Go over test Circular motion

22 23 24 25 26

Go over test Circular motion

Circular Motion Gravitation

QUIZ: Circular Motion, Gravitation

29 30 31 November 1 2

Go over quiz Test review

TEST: Circular Motion, Gravitation Go over Test Momentum & Impulse

5 6 7 8 9

Go over Test Momentum & Impulse

Finish Momentum & Impulse QUIZ: Momentum & Impulse

Go over quiz Conservation of Momentum (COP)

12 13 14 15 16

Conservation of Momentum QUIZ: Conservation of Momentum Go over quiz

Flex Day

19 20 21 22 23

Thanksgiving

26 27 28 29 30

Flex Day Test review TEST: Momentum, Conservation of Momentum

December 3 4 5 6 7

Go over test Energy, Work & Power

QUIZ: Energy, Work & Power Semester Exam Review

10 11 12 13 14

Semester Exam Review

Semester Exam Review Semester Exam Review

17 18 19 20 21

Exam 2A, 4A

Exam 2B, 4B

Exam 1st, 3A Early Release

Exam 3B, 5th Early Release

No school

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Physics Formulas

Linear Motion

1 Speed and Velocity (m/s) 𝑣 =𝑑

𝑡

2 Acceleration (m/s2) 𝑎 =𝑣𝑓 − 𝑣𝑖

𝑡

The 4 Equations of Constant Acceleration (Kinematic Equations)

3 𝑣𝑓 = 𝑣𝑖 + 𝑎𝑡

4 𝑑 =1

2(𝑣𝑓 + 𝑣𝑖)𝑡

5 𝑑 = 𝑣𝑖𝑡 +1

2𝑎𝑡2

6 𝑣𝑓2 = 𝑣𝑖

2 + 2𝑎𝑑

Force

7 Net Force (N) Σ𝐹 = 𝑚𝑎

8 Frictional Force (N) 𝐹𝑓 = 𝜇𝐹𝑁

9 Weight (N) 𝐹𝑔 = 𝑚𝑔

Circular Motion & Gravitation

10 Circular Speed (m/s) 𝑣 =2𝜋𝑟

𝑇

11 Centripetal Acceleration (m/s2) 𝑎𝑐 =

𝑣2

𝑟

12 Centripetal Force (N) 𝐹𝑐 = 𝑚𝑣2

𝑟

13 Gravitation (N) 𝐹𝐺 = 𝐺𝑚1𝑚2

𝑟2

Momentum

14 Momentum (kg·m/s) 𝜌 = 𝑚𝑣

15 Impulse-Momentum Theorem (impulse: N·s) 𝐽 = 𝐹𝑡 = 𝑚(𝑣𝑓 − 𝑣𝑖)

Work, Power, Energy

16 Work (J, N·m) 𝑊 = 𝐹𝑑

17 Work-Energy Theorem 𝑊 = ∆𝐸 = 𝐸𝑓 − 𝐸𝑖 = 𝐹𝑑

18 Power (J/s or W) 𝑃 =𝑊

𝑡=

𝐹𝑑

𝑡=

𝑚𝑎𝑑

𝑡

19 Kinetic Energy (J) 𝐾𝐸 =𝑚𝑣2

2

20 Gravitational Potential Energy (J) 𝑃𝐸 = 𝑚𝑔ℎ

Thermal Energy & Temperature

21 Thermal Energy for Temperature Change (J) 𝑄 = 𝑚𝑐(∆𝑇)

22 Thermal Energy for Fusion/Melting (J)

𝑄 = 𝑚𝐻𝑓

23 Thermal Energy for Vaporization/Condensation (J) 𝑄 = 𝑚𝐻𝑣

24 Kelvin to Celsius 𝐾 = ℃ + 273

Electricity

25 Electrostatic Force (N) 𝐹𝐸 = 𝑘𝑞1𝑞2

𝑑2

26 Electric Power (W) 𝑃 = 𝐼𝑉 = 𝐼2𝑅 = 𝑉2

𝑅

27 Electric Energy (J) 𝐸 = 𝑃𝑡 = 𝑉𝐼𝑡 = 𝐼2𝑅𝑡 = 𝑉2

𝑅𝑡

28 Current (A) 𝐼 =𝑉

𝑅=

𝑞

𝑡

29 Equivalent resistance in a series circuit (Ω) 𝑅𝑇 = 𝑅1 + 𝑅2 + 𝑅3 …

30 Equivalent resistance in a parallel circuit (Ω)

1

𝑅𝑇=

1

𝑅1+

1

𝑅2+

1

𝑅3…

Waves & Optics

31 Frequency (Hz) & Period (s) 𝑓 = 1

𝑇 𝑇 =

1

𝑓

32 Wave speed (m/s) 𝑣 = 𝑓𝜆

33 Speed (m/s) 𝑣 =𝑑

𝑡

34 Index of Refraction 𝑛 = 𝑐

𝑣

35 Snell’s Law of Refraction 𝑛1 sin 𝜃𝑖 = 𝑛2 sin 𝜃𝑟

36 Critical Angle, ° 𝜃𝑐 = sin−1 {𝑛2

𝑛1}

Nuclear Energy

37 Mass-Energy Equivalence (Einstein’s Equation) 𝐸 = 𝑚𝑐2

Constants

38 G = Gravitational Force constant 6.67x10-11

39 g = acceleration due to gravity (earth) -9.8 m/s2

40 k = Electrical Force constant 9 x 10 9

41 Charge of an electron -1.6 x 10-19 C

42 Specific Heat of Water 4186 J/kg·K

43 Specific Heat of Ice 2100 J/kg·K

44 Specific Heat of Steam 2010 J/kg·K

45 Heat of Fusion (Water) 3.33 x 105 J/kg

46 Heat of Vaporization (Water) 2.26 x 106 J/kg

47 Speed of Sound in air (at normal temp. and pressure) 340 m/s

48 c = Speed of Light in a vacuum 3 x 108 m/s

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Unit 2 Homework Problems Circular Motion

1. What force is providing the centripetal force in each of the following examples? a. A car going around a curve b. You are spinning in circles and feel pressed against the car while riding the tilt-a-whirl at a carnival c. David whirled a stone over his head in a sling before launching it at Goliath d. A child twirling a ball on a rope e. The moon orbiting the earth

2. What is the most common (and false) explanation for why you feel “pulled” to the outside of the curve when you are rounding a bend in the road?

a. What is the true and accurate explanation for this phenomenon? 3. As the linear speed of an object in circular motion increases, the centripetal force {increases, decreases, remains

the same}, while the period {increases, decreases, remains the same} and the centripetal acceleration {increases, decreases, remains the same}.

4. A jet traveling at 594 m/s makes a turn with a radius of 6000 m. What is the plane’s acceleration? [58.8] a. If acceleration due to gravity (“g”) is 9.8 m/s2, how many g’s (multiples of “g”) does the pilot experience?

How does this affect his apparent weight (does he feel heavier, lighter, or normal)? [6 g’s] 5. A 0.25 kg mass is attached to a 1.5 m long string. The mass is moving in a horizontal circle with a speed of 7.85

m/s. What is the tension in the string? [10.3] 6. A 1500 kg car rounds a corner with a radius of 25 m. If the friction force between the pavement and the tires in

7350 N, what is the maximum speed that the car can take the corner? [11.07] 7. It takes a 615 kg race car 14.3 seconds to travel at a uniform speed around a circular racetrack with a 50.0 m

radius. a. What is the car’s speed? [21.97] b. How much force must the track exert against the tires to produce this acceleration? [5937]

8. A rubber stopper on the end of a 0.5m long string completes 10 circles in 5 seconds. a. What is the velocity of the rubber stopper? [6.28] b. What is the centripetal acceleration of the stopper? [78.9]

9. A 0.1 kg ball on the end of a 0.6 m long string is swung in a horizontal circle. a. What is the maximum speed of the ball if the string will break when 100 N of tension is placed on it? [24.5] b. At this speed, calculate the period. [0.15]

10. For the following scenarios, state which force is causing the object to move in a circular path (what force is providing the centripetal force?).

a. Car going around a curve b. Ball on a String

c. Earth orbiting the Sun d. Electron orbiting the nucleus

Universal Gravitation 11. Deimos, a satellite of Mars, has an average radius of 6300 m and a mass of 1.48 x 1015 kg. Calculate the

gravitational force between Deimos and a 3.0 kg rock at its surface. [0.0075] 12. The moon is approximately 3.8 x 108 m away from earth. If the earth has a mass of 6.0 x 1024 kg and the moon

has a mass of 7.3 x 1022 kg, what is the magnitude of the gravitational force between them? [2.0 x 1020] a. What would happen to the gravitational force between them be if the earth’s mass was decreased?

13. What happens to the force of gravity between two objects if: a. The mass of one object increases? b. The masses of both objects increase?

c. The distance between the masses is increased? d. The distance between the masses is decreased?

14. Circle all of the following that are FALSE. Explain your reasoning. a. The earth exerts a gravitational force on you. b. You exert a gravitational force on the earth. c. The earth pulls harder on you than you are pulling on the earth. d. You pull harder on the earth than the earth is pulling on you. e. You and the earth attract each other with equal forces in opposite directions. f. You experience the greater acceleration because the earth pulls harder on you. g. You experience the greater acceleration because the earth is not free to move. h. You experience the greater acceleration because you have less mass.

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Momentum & Impulse

15. Which of the following objects have momentum? Include all that apply. a. An electron orbiting the nucleus of an atom. b. A UPS truck stopped in front of the school building. c. A compact car moving with a constant speed. d. A small flea walking with constant speed across Fido's back. e. The high school building resting in the middle of town.

16. In order to catch a ball, a baseball player naturally moves his or her hand backward in the direction of the ball's motion once the ball contacts the hand. This habit causes the force of impact on the players hand to be reduced in size principally because ___.

f. the resulting impact velocity is lessened g. the momentum change is decreased h. the time of impact is increased

i. the time of impact is decreased j. none of these

17. How does an airbag save your face? In your explanation use the following terms: force, time of impact, impulse, change in momentum.

18. A 4 kg object has a momentum of 12 kg•m/s. What is its speed? [3] 19. A 0.17 kg softball is traveling at 30.0 m/s when caught. If the force of the glove on the ball is 505 N, what is the

time it takes the ball to stop? [0.01] 20. An 80.0 N force accelerates a 5.0 kg object from 2.0 m/s to 8.0 m/s. What is the impulse? [150] 21. An impulse of 150 Ns is required to stop a person’s head in a car collision. If the face is in contact with the

steering wheel for 0.020 seconds, what is the force on the cheekbone? [7500] 22. A 0.16 kg baseball thrown at 40.0 m/s is hit directly back in the opposite direction at 55 m/s. If the bat is in

contact with the ball for 0.0030 seconds, what is the force exerted on the ball? [-5066.7] 23. How much momentum does a 3500 kg truck have when traveling 2.36 m/s? [8260] 24. A 0.530 kg basketball hits a wall head-on with a forward speed of 18.0 m/s. It rebounds with a speed of 13.5

m/s. The contact time is 0.100 seconds. (a) determine the impulse with the wall, (b) determine the force of the wall on the ball. [impulse: -16.7; force: -167 ]

25. A 0.06 kg tennis ball, initially at rest, is hit by a racket. It leaves the racket with a velocity of 33.6 m/s. If the time that the racket and ball are in contact with each other is 0.06 sec, what force is required to move the ball? [33.6]

Conservation of Momentum 26. The firing of a bullet by a rifle causes the rifle to recoil backwards. The speed of the rifle's recoil is smaller than

the bullet's forward speed because the ___. a. Force against the rifle is relatively small b. Speed is mainly concentrated in the bullet c. Rifle has much more mass

d. Momentum of the rifle is unchanged e. None of these

27. If Mr. Hopkins (a big dude) jumps off a rolling chair, which of the following will happen? (choose all that apply) f. He will break his neck g. His momentum will be more than the

chair’s h. His momentum will be less than the

chair’s i. His momentum will be the same as the

chair’s

j. His speed will be less than the chair’s k. His speed will be greater than the

chair’s l. He will have the same speed as the

chair

28. Moving at 20.0 m/s, a 705 kg car collides with a stationary 1400 kg truck. If the two vehicles interlock, what is their velocity together? [6.7]

29. A 0.50 kg red ball traveling at 6.0 m/s collides with a 0.65 kg blue ball that is at rest. After the collision the red ball’s velocity is 3.8 m/s. What is the velocity of the blue ball? [1.7]

30. A 0.200 kg purple ball moves across the table with a velocity of 0.30 m/s. It collides with a 0.200 kg green ball moving in the same direction at 0.10 m/s. After the collision, the velocity of the purple ball is 0.26 m/s. What is the velocity of the green ball? [0.14]

31. A 25 kg Ewok is sitting in a frictionless mud hole. If he throws a 6 kg rock to the right at a speed of 15 m/s, how fast and in what direction will he move? [3.6 left]

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32. A car with a mass of 450 kg is moving to the right at 20 m/s and collides with a 600 kg truck moving to the left at 20 m/s. In the collision, they lock together. What is the velocity (speed and direction) of the pair after the collision? [2.86 left]

Work, Power, & Energy 33. How much work is required to lift a 2.5-kg object to a height of 6.0 meters? [147] 34. Eddy, who’s mass is 65.0 kg, climbs from the ground up the 1.60 m high stairs in 1.20 s.

a. What is his change in potential energy? [1019.20] b. How much work did he do to climb the stairs? [1019.20]

35. Pete applies a 11.9 N force to a 1.49 kg mug of root beer in order to accelerate it from rest over a distance of 1.42 m. How much work was done on the mug? [16.9]

36. 345 J of work is done to push a couch 4 m across the floor. How much force was exerted? [86.3] 37. Calculate the kinetic energy of a 1.5 kg ball moving at 18 m/s. [243] 38. A monkey swinging on a vine at 20 m/s has 800 J of kinetic energy. What is the monkey’s mass? [4] 39. For P.E. class, a 64 kg student has to climb a rope to the top of the gym. The gym ceiling is 6 m high. It takes

the student 45 seconds. a. How much work was done by the student? [3763.2] b. What is the student’s power? [83.6]

40. A 100 kg wrecking ball is lifted and is going to be dropped on a 3-story building to demolish it. If it needs 25,000 J of potential energy to fall through all 3 floors, how high must if be lifted before it is dropped? [25.5]

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Name _______________________________________________________

NOTES, Circular Motion (Centripetal Force, Centripetal Acceleration, & Speed)

Review: Newton’s laws

• An object moving in a circular path is continuously changing direction, and therefore it is __________________________________.

• Newton 2: Acceleration can only happen if an __________________________________ is applied

• Which direction will an object travel if the force ceases? __________________________

Centripetal Force:

• A force that causes an object to

keep moving

____________________

_________________________

• The centripetal force is

provided by a specific force • This force is a pull towards the

_________________ of the circle (centripetal means “________________________

__________________”) Centripetal Acceleration

• An object moving in a circular

path is constantly ______________________________

• Centripetal acceleration is always toward the __________________________________

Circular motion equations • Centripetal Acceleration:

ac = centripetal acceleration (m/s2) v = velocity (m/s) r= radius (m)

• Centripetal Force:

Fc = force in newtons m = mass in kg

v = velocity in m/s r = radius in meters

Speed of Circular Motion

• v = velocity (m/s)

• r = radius of the circle (m) • T = period (sec/revolution)

Velocity

Velocity

Velocity

Velocity

6

Name _______________________________________________________

Period (T) • Sometimes information may be given in RPM (__________________________________)

• Must convert to T (sec/rev); flip the number and convert from minutes to seconds. • Ex.:The tachometer in your car reads 5000 RPM. What is the period?

Sample Problems A rubber stopper on the end of a 0.5m long string completes 10 circles in 5 seconds. What is the

velocity of the rubber stopper?

How much centripetal force (gravity) does it take to hold an 80 kg person to the surface of the earth

at the equator, which is rotating at 460 m/s with a radius of 6,371,000 m?

Centripetal Force vs Centrifugal Force

• Why do you always feel “pulled” toward the outside of a turn?

o ____________________. This is sometimes known as “centrifugal force”

o THIS IS NOT A REAL FORCE!

▪ Why? It has no ___________________. Nothing is “pulling” you.

• ________________________ is a real force. “Centrifugal force” is a real phenomenon but is

NOT a real force.

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8

Name ______________________________________________________ Period____________ Lab – Centripetal Force

Purpose: To experimentally determine how the speed changes as the centripetal force is increased. 1. Measure and record the distance from the middle of the stopper to the upper end of the tube.

This should be approximately 1 m. Use the clip on the lower end of the tube to set this distance. 2. Measure the mass of your stopper: mass of stopper = ____________ 3. Hang the 100 g mass from the paperclip on the end of the string. 4. Whirl the stopper above your head in a horizontal circle (please be careful not to hit anyone).

When the stopper is traveling at the desired speed, the clip will stay just below the bottom of the tube. DO NOT ALLOW THE CLIP TO TOUCH THE TUBE.

5. Use a stopwatch to determine the time it takes for the stopper to complete 10 revolutions. 6. Repeat steps 2-4, adding an additional 50 - 100 g each time. DO NOT HANG MORE THAN 500 g!

Fill in the data table below. Data & Calculations (show all calculations below the table).

Mass hanging (kg)

Weight of the hanging mass

(N)

Total time for 10 revolutions

(sec)

Period (sec)

Speed (m/s)

FT (N)

1. Describe the motion of the stopper if the string were cut while you were revolving it.

2. Using your calculations for your FIRST trial (the 1st row in the table):

a. Draw and label the forces that are acting on the stopper:

b. Calculate the magnitudes of each of the forces in your diagram.

3. Using the terms centripetal force, weight, gravitational force, and speed, explain why you had to spin the stopper faster when you added more mass to the end.

string

9

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Name ______________________________________________________ NOTES – Newton’s Law of Universal Gravitation

• Describes ______________________________________________________________________

______________________________________________________________________________

• Every object puts a gravitational force on every single other object

• “Universal” means everywhere in the universe – i.e., gravity exists, even in space Gravitation

• Every mass attracts every other mass by a force (this force is ______________________!)

• Objects “wants” to be pulled toward each other object, therefore gravity is an attractive force

• This force points along an imaginary line connecting the two masses. Gravity and Newton’s Laws of Motion

• You and the earth both exert a gravitational force on each other. Which is greater – your pull on the earth or the earth’s pull on you?

o __________________________________________________

• Newton’s 3rd law states that the forces that you exert on each other must be ___________________.

• Why doesn’t it seem like the forces are equal?

o The _______________________________ that results from that force is drastically different for you than it is for the earth.

o The difference in acceleration is explained by the difference in ______________, which is stated in Newton’s 2nd law.

▪ The higher the mass, the _________________ the acceleration Gravitational “Constant”

• When Newton came up with the Law of Universal Gravitation, he discovered a new “constant” which he called

the “___________________________________________________________”

• This constant has a value of: o G = __________________________

Gravitation Equation:

• FG = Force of Gravity (N) • G = “Universal Gravitation Constant” = ________________________________

• m1 = mass of the first object (kg); m2 = mass of the second object (kg)

• r = distance between the objects (m) Sample Problem #1

• You and your boyfriend / girlfriend each have a mass of 60kg, and the two of you are sitting 20 cm apart. Calculate the gravitational attraction force between you.

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Name ______________________________________________________ Sample Problem #2

• Ex: If you have a mass of 55 kg, calculate the force of gravity you feel from the moon when standing on the moon’s surface. The mass of the moon is 7.4 x 1022 kg, and the radius of the moon is 1.74 x 106 m.

Universal Gravitation Equation: proportionality

• The force of gravity between 2 objects is determined by what 2 things?

• ___________________________________ _______________________________________

• Mass is _____________________ proportional to the force

o This means that when mass increases, the force ______________________, and vice-versa.

o It’s about the PRODUCT of the mass, so it doesn’t matter if one or both masses change.

• Distance is ____________________________ proportional to the force.

o This means that when distance increases, the force ______________________, and vice-versa.

o Changes in distance have a greater effect on the force than changes in mass. Why?

▪ _________________________________________________

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Test Review: Circular Motion and Gravitation CONCEPTS

1. A car is moving at a constant speed of 40 mph around a circular track. Is the car accelerating? Why or why not?

2. What is providing the centripetal force in each of the following examples? a. A person “stuck” to the wall on the gravitron ride at the fair. b. A stone being twirled in a circle at the end of a rope c. The International Space Station in orbit d. A car rounding a curve in the road

3. What specific force is providing the centripetal force for the moon in orbit? What is the direction of that force? What would happen to the moon if that force suddenly stopped acting?

4. What are the two factors that determine the amount of gravitational force between 2 objects? 5. Considering what you know about the gravitation equation, explain why you weigh less on the moon

even though you have the same mass. 6. The gravitational force is an attractive force between two objects because of their _____. 7. The earth attracts the moon with a gravitational force, and the moon is also pulling on the earth.

a. Compare or contrast the magnitudes of these two forces and explain why they are the same or different using one of Newton’s laws of motion.

b. Compare or contrast the magnitudes of the centripetal acceleration of the earth and of the moon as a result of their gravitational force on each other and explain why they are the same or different using one of Newton’s laws of motion.

c. If the moon mass was suddenly greatly increased, what would happen to the magnitude of the gravitational force between the two?

d. If the moon somehow drifted much farther away from the earth, what would happen to the magnitude of the gravitational force between the two?

8. Which of these would cause a greater change in the gravitational force between 2 objects, and why? a. Doubling the product of their masses b. Doubling the distance between them

CIRCULAR MOTION 9. A 2.0 kg ball is attached to a 1.5 m long string and swung in a horizontal circle at a constant speed of

12 m/s. a. Draw and label vectors for velocity, centripetal acceleration, and centripetal force. The object is

traveling counter clockwise. b. What is the centripetal acceleration of the ball (include direction)? (96 m/s2, towards the center) c. What is the tension in the string? (192 N)

10. A 60-kg speed skater on roller blades comes into a curve with a 20 m radius at a speed of 18.0 m/s. How much friction must be exerted between the wheels and the ground to successfully round the curve? (972 N)

11. What is the period of rotation of a fan blade that completes 235 rotations in 60 seconds? [0.26 sec] a. What is the speed of the outermost point on the fan blades, which is 0.132 m from the center of

the fan? [3.2 m/s] b. At this speed, what is the centripetal acceleration of a bug hanging on to this point on the

blade? [77.6] 12. A 1.2 kg rock is being swung in a circle at the end of a 1.3 m long string. Calculate the amount of

tension force the string must be able to withstand without breaking if the rock is making 28 circles in 10 seconds. [483 N]

UNIVERSAL GRAVITATION 13. Two satellites each have a mass of 1600 kg and are put into orbit around each other 30 m apart.

Calculate the gravitational force between them. [1.9 x 10-7 N] 14. The mass of Saturn is 5.7 x 1026 kg. It’s largest moon, Titan, has a mass of 1.3 x 1023 kg and is

orbiting so that its center of mass is approximately 1.3 x 109 m away from that of Saturn. Calculate the force of gravity between the two. [2.9 x 1021 N]

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Name________________________________________________________ NOTES-Momentum, Impulse, Conservation of Momentum Momentum is ___________________________________________________________________________________

__________________________________________________________________________________________________

Formula for calculating momentum:

****Unit: ___________________****

Change in Momentum (Δρ) How can you change the momentum of a moving object ?

Change its _________________________ and/or change its _____________________.

Impulse is- ______________________________________________________________________________________.

It is the product of ______________________________ and ________________________________________________

Formula for calculating impulse: ***Unit: ______________________***

Relationship between Impulse and Momentum: The Impulse-Momentum Theorem Check for Understanding:

1. You jump and land with your knees bent, then you jump and land with your knees locked. They each have the same momentum. Which one has the greater impulse? ______ Which one had the larger force? _________ Which one had the longer time? _________ How are force and time related? ________

2. If you want a bigger change in momentum, you must have a bigger impulse. What are 2 ways that you can increase the magnitude of the impulse?

Problem: A 0.40 kg football is sitting on a tee. It is kicked and leaves the tee with a speed of 12.4 m/s. What impulse did it receive from the kicker? Problem: A 0.25 kg tennis ball traveling at 12.2 m/s is hit. Its return speed is 14.2 m/s. If the ball is in contact with the racket for 0.012s, how much force is applied?

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Name________________________________________________________ NOTES-The Law of Conservation of Momentum Whenever 2 objects collide, the momentum lost by one object is gained by the other object. The total momentum of the system . Law of Conservation of Momentum can be best illustrated by collisions. There are 3 types of collisions: 1) Bouncing collision

Before: After: If the objects bounce off each other, there are _____ separate objects before the collision and _____ objects after. 2) Locking Collision If the objects stick to each other, there are _____ separate objects before the collision and _____ objects after. 3) Explosions Any 2 objects are at rest and then move apart as a result of energy that is released between them.

Examples: ___________________________________________________________________

In an explosion, there are _____ separate objects before the collision and _____ objects after.

at rest

m = 0.50 kg v = 0.50 m/s ρ = mv = _____

m = 0.25 kg v = 0 m/s

ρ = mv = _____

Total ρ = _____

m = 0.50 kg v = 0.40 m/s

ρ = mv = _____

m = 0.25 kg v = _______m/s

ρ = mv = _____

Total ρ = _____

at rest

m = 3.0 kg v = 2.2 m/s

ρ = mv = _____

m = 3.0kg v = 0 m/s

ρ= mv = _____

Total ρ = _____

m = _____ kg v = ______m/s ρ = mv = _____

Total ρ = _____

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at rest

m = 8.0 kg v = _____ m/s

ρ = mv = _____

m = 1.5 kg v = 14 m/s

ρ= mv = _____

Total ρ = _____

m = _____ kg v = ______m/s

ρ = mv = _____

Total ρ = _____

15

Name________________________________________________________ Problem: A 0.50 kg ball moving at 0.75 m/s collides with a 0.60 kg ball at rest. After the collision, the velocity of the first ball is 0.25 m/s. What is the velocity of the second ball? Problem: A toy engine with a mass of 1.5 kg and a speed of 2.0 m/s collides with a second engine with a mass of 1.0 kg at rest. They lock together. What is the velocity of the pair after the collision? Problem: A bullet with a mass of 0.05 kg leaves the muzzle of a gun with a mass of 4.0 kg with a velocity of 400 m/s. What is the recoil velocity of the gun?

16

Name _________________________________________________________________ Pd_______________

Test Review: Momentum & Impulse, Conservation of Momentum Answer the questions on a separate sheet of paper CONCEPTS 1. How do you calculate the momentum of an object? 2. How can two objects of different mass still have the same momentum? How can an object with small mass have

more momentum than an object with greater mass? 3. How do airbags protect a person in a car accident? 4. Why is it necessary for a baseball to compress (squish) when it is hit by a bat? 5. When you catch an egg moving at 4 m/s by cradling it, the impulse applied to the egg by your hand is (greater than /

the same as / less than) the impulse that would be applied to it if it smacks into a wall. Explain (be specific). 6. When a golf club hits a golf ball, the change in momentum of the ball is _____ the change in momentum of the club

head. (equal to, less than, or greater than) 7. Why do fire hoses recoil (move backward) when the water is turned on? Which of Newton’s laws does this relate to? 8. You are standing on a skate board and is holding a heavy bowling ball. If he throws the ball horizontally forward,

what will be his resulting motion? [A] Forward [B] no motion [C] Backward [D] You’ll fall down. Cause you’re a klutz.

PROBLEMS 9. What is the momentum of a 0.124 kg baseball traveling at +40 m/s? (ANS: 4.96 kg•m/s) 10. What speed would a 0.03 kg rat need in order to have the same momentum as a 0.75 kg chicken running at a speed

of 1.8 m/s? [45 m/s] 11. What impulse is needed to stop a 0.031 kg mass traveling at a velocity of –38 m/s (ANS: 1.2 N•S) 12. A force with magnitude of 447 N is used to stop an object with a mass of 61 kg moving at a velocity of +132 m/s.

How long will it take to bring the object to a full stop? (ANS: 18s) 13. A metal sphere with a mass of 64.0 kg rolls along a frictionless surface at 18.0 m/s and strikes a stationary sphere

having a mass of 270.0 kg. The first sphere stops completely. At what speed does the second sphere move away from the point of impact? (ANS: 4.3 m/s)

14. In running a ballistics test at the police department, Officer Rios fires a 0.006 kg bullet at 340 m/s into a container that stops it in 0.29 sec. What force stops the bullet? (ANS: -7.0 N)

15. A 0.05 kg cart is attached by a compressed spring to a 4.65 kg cart at rest. When the spring is released, the first cart moves to the right with a velocity of 47 m/s. What is the velocity of the second cart? (ANS: -0.5 m/s)

16. A 0.012 kg rubber bullet travels at a velocity of 133 m/s, hits a stationary 8.3 kg concrete block resting on a frictionless surface, and bounces off in the opposite direction with a velocity of –91 m/s. How fast will the concrete block be moving? (ANS: 0.32 m/s)

17. A 6200 kg freight car traveling at 2.2 m/s collides with an 8200 kg stationary freight car. If they interlock upon collision, find their velocity. (ANS: 0.95 m/s)

18. A 24.0 kg dog running at a speed of 3.0 m/s jumps onto a stationary skateboard that has a mass of 3.6 kg. How long will it take an average force with a magnitude 9.0 N to stop the skateboard and dog? (ANS: 8s)

19. A 0.020 kg bullet enters a 3.01 kg watermelon and remains lodged there. The melon is immediately set into motion with a speed of 3.47 m/s. What was the entry speed of the bullet? (525.7 m/s)

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Name _______________________________ Pd _________

People Power Lab - Calculating Work and Power

Purpose The purpose of this experiment to determine the work done and power exerted in a trip up a set of stairs. Procedure Each person MUST collect his/her own set of data; you can work alone or with a partner. Everyone will weigh themselves and everyone will run up the stairs. 1. Use a scale to weigh yourself if you do not know your weight. Record your weight in the space provided below and

convert it to newtons by multiplying by 4.45. Your weight is equal to the force your legs must exert to climb up one step. Record this force in the data table.

My weight is:________________ lbs x 4.45 N/lb = _________________ N

2. Measure the height of one step in meters, multiply this by the number of steps you climbed to find vertical height. Consider this to be your distance.

3. Using a stopwatch, time yourself walking up the flight of stairs. Record this time in the data table.

4. Now time yourself running up the THE SAME flight of stairs. Record this time in the data table.

Data Table

Trial Distance (m) Force (N) Work (J) =

Force x Distance Time (s)

Power (W) =

Work Time

Walk

Run

Questions (Answer briefly but completely)

1. Was there a difference in the work done for walking and running? Why or why not?

2. Was there a difference in the power used for walking and running? Why or why not? 3. Which activity, walking or running, involved more power? Why? 4. If you had climbed more slowly, how would the amount of work done been affected? Explain your answer fully.

5. Suppose you and a friend each mow a different lawn in the same amount of time. However, the lawn you mowed is

larger. Which person performed more work? Explain your answer fully. 6. In the situation in question five, which person exerted a greater amount of power? Explain your answer fully. 7. If one food Calorie equals 4184 J of energy, then to what vertical height would an 80 kg person have to climb to burn

off the 50 Calories from one cream-filled cookie?

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Name ___________________________

Notes – Energy, Work & Power

Energy Energy is the ability to produce ________________________________________________________________________

It is also the ability to do _________________. The unit for energy is _________________________

Kinetic energy is energy due to ____________________________________

Potential energy is __________________________________

Formulas: KE = m =

KINETIC ENERGY: v =

GRAVITATIONAL PE = m = POTENTIAL ENERGY: g = h = Objects store gravitational potential energy when they are held some distance above the Earth’s surface

Example Problems:

1) An 875 kg car is traveling at 44.0 m/s while passing another car. How much kinetic energy does it have?

2) A 50.0 kg ball is shot from a cannon to a height of 425 m. How much gravitational potential energy does it have?

3) A football player has 550 J of kinetic energy while running at a speed of 10 m/s. What is his mass?

Work 3 definitions (only 2 now, 3rd later): 1) When a force moves an object through a ___________________ against another force.

2) When a force causes ____.

Formula for Work: W = F = d =

• ONLY forces that are applied _______________________ to the direction of motion are considered when calculating work.

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Name ___________________________

Examples:

• If a force of 100 N was exerted on an object and no work was done, the object must have ____. A accelerated rapidly B remained motionless C decreased its velocity D gained momentum How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N?

How much work must a crane do to lift a 75 kg steel beam to a height of 8 m?

Power • Power: the ____________ at which work is done

Formula for Power: P = W = t =

Examples: • A machine performs 500 Joules of work over a period of 100 seconds. Calculate its power output.

• An electric motor lifts an elevator 9.0 m in 15 s by exerting an upward force of 12,000 N. What power does the motor produce?

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Review: Physics Fall Semester Exam (Do this on notebook paper) Nature of science 1. What is science? 2. Name some limitations of science. 3. What can science help us learn about? What can science NOT help us learn about? 4. What is the difference between a hypothesis and a theory? Theory and Law? Be able to recognize examples of each. 5. What is the metric (SI) system? Why do we use it? 6. Be able to recognize common SI system units and differentiate them from common US customary units. Distance/Displacement, Speed/Velocity 7. Distance vs Displacement: How are these two words are similar and how they are different? How could knowing the

difference between these two terms help you solve physics problems? 8. If drive at 35 m/s for 15 minutes (900 sec), how far will you have traveled? (31,500 m) 9. How fast is a car traveling that covers 400 m in 5.2 sec? [76.9m/s] 10. Susie Q decided to go meet her friends at the local pool. Susie walks 3 blocks west and 2 blocks north.

a. What was the distance Susie walked? (5 blocks) b. What was her displacement? (3.61 blocks NW)

11. Sound moves at a constant speed of 340 m/s. If a person shouts across a 550 m wide canyon to someone on the other side, how long will it be before the person on the other side hears it? [1.6 sec]

Acceleration & Motion Graphs 12. What is the definition of acceleration? 13. What are the 3 ways to accelerate? 14. Determine whether the acceleration for the following situations is positive or negative.

a. Positive velocity, and slowing down= _________ acceleration

b. Negative velocity, and slowing down= _________ acceleration

c. An object being thrown up in the in air = _________ acceleration

d. An object falling in the air = _________ acceleration

15. If an object is accelerating from rest at a rate of 10 𝑚

𝑠⁄

𝑠, what

will be its speed at: a. t=2 sec? b. t = 3 sec? c. t = 10 sec?

16. An object is dropped in a vacuum chamber (no air). How fast is it going at t=1 sec? t=2 sec? 17. Use the velocity vs time graph to answer the following questions.

a. When is this object gaining speed? Slowing down? b. When is the object moving forward? Backward?

18. Use the position vs time graph to answer the following questions. a. When is the object at rest? Moving forward? Moving

backward? b. What is the speed of the object during the first 10 sec? [6

m/s] c. Give 2 other labels you might see for the y axis of this

graph. 1-D Kinematics 19. True or False: If a feather and a hammer are dropped from the

same height, in a vacuum (no atmosphere, but still have gravity), they will reach the ground at the same time. 20. Give the number(s) of the equation(s) in the chart that can be used to solve motion problems with constant speed. 21. Give the number(s) of the equation(s) in the chart that can be used to solve motion problems with changing speed. 22. An orange falls from rest and strikes the ground 8 seconds later. What is the final velocity of the orange the instant

before it hits the ground? (78.4 m/s) 23. How long does it take a rock to hit the water if it was dropped from a height of 10 m? (1.43 sec)

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2-D Kinematics (Projectiles) 24. A bullet fired horizontally hits the ground in 0.5 seconds. If it had been fired with twice the speed in the same

direction, would it have hit the ground in (assume no air resistance) 0.5 sec, <0.5 sec, or >0.5 sec? 25. What happens to the horizontal speed of a projectile? Why? 26. What happens to the vertical speed of a projectile? Why? 27. How are the horizontal and vertical components of a projectile’s motion related to each other? 28. If a ball is thrown at 20 m/s horizontally off the top of a 30 m high tower,

a. How long will it take to hit the ground? (2.47 sec) b. How far will it land from the base of the tower? (49.4 m)

29. ALL these questions can be answered without a calculator: Ronald McDonald runs off a cliff with a speed of 10m/s… a. What is his vertical velocity as it leaves the cliff? b. What is his horizontal velocity as it leaves the cliff? c. What is his horizontal velocity half way down the cliff? d. What is his horizontal acceleration? e. What is his vertical acceleration? f. If Hamburglar is next to Ronald and is dropped off the cliff at the same time, which one hits the ground

first? Newton’s Laws/ Forces 30. Know Newton’s 3 laws and understand what they mean and what scenarios they apply to. 31. Which of newton’s laws explains why you are not falling through your chair? 32. An object with less mass will experience ____ acceleration with the same force applied? (more or less)

a. This refers to which of Newton’s Laws? 33. How is an object’s mass related to its acceleration? (directly or indirectly?) 34. How is the force acting on an object related to its acceleration? 35. When acceleration is zero what is true of the forces acting upon an object? 36. Draw a free body diagram of an object: a)speeding up b)slowing down c)moving at a constant speed 37. When object A pushes on object B, object B pushes back on A with an equal force in the opposite direction. Which of

Newton’s laws is this? What would be an example of this? 38. Write the Law of Inertia. Which law is this? Give an example of it. 39. What is the most common example of Newton’s 3rd law? 40. I’m pushing a box with a force of 100N. If the box moves forward but has a constant velocity, what is it’s

acceleration? How is that possible? 41. If an object is accelerating, the forces acting on it must be __. 42. If an object is moving at a constant speed, the forces acting on it must be ___. Another way to say this is that the net

force = __. 43. What are 2 things an object can be doing to have zero acceleration. 44. What 2 things MUST BE true about an object in equilibrium? 45. A 50kg crate is pushed forward so it accelerates at 0.3 m/s2. What is the net force acting on the crate? (ANS: 15N)

a. If the applied force is 185 N, calculate the friction force in this situation. [-170 N] 46. A girl is holding the end of a bungee cord that has a 0.45 kg block attached to the other end. She drops the block,

but still holds the free end of the cord. As the block nears the bottom of its drop, the cord pulls upward with a force of 7.5 N in order to slow the block down before it hits the ground. Calculate the acceleration of the block at this point (Hint: first calculate the block’s weight, Fg). [6.9 m/s2]

47. Name at least 7 types of forces and tell when and where (specifically) they act. 48. What does friction do? Which direction does it act? Circular Motion 49. What keeps the moon going around the earth? What is the direction of that force? What would happen to the moon

if that force suddenly switched off? 50. What is the name of the force that causes objects to move in a circular path? 51. Is circular motion natural? Why or why not? 52. If you are going around a curve on your bike at a constant speed, are you accelerating? Why or why not? 53. As you swing a cup of water in a vertical circle, explain why the water doesn’t come out of the cup.

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54. How is mass related to centripetal force? (directly or indirectly?) 55. How is speed related to centripetal force? 56. How is the radius of the circle related to centripetal force? 57. A 2.0-kg ball is attached to a 1.5-m long string and swung in a horizontal circle at a constant speed

of 12 m/s. a. Draw a picture of this ball and label vectors for velocity, centripetal acceleration, and

centripetal force. The object is traveling counter clockwise. b. What is the centripetal acceleration of the ball (include direction)? (96m/s2, towards the center) c. What is the tension in the string (include direction)? (192N, towards the center) d. A 60-kg speed skater with a velocity of 18.0 m/s comes into a curve with a 20-m radius. How much

friction force must be exerted between the skates and ice to negotiate the curve? (972 N) Universal Gravitation 58. Considering the earth and the moon, they attract each other with a gravitational force. Which of the two is

experiencing a greater attractive force? Which of the two is experiencing a greater acceleration? Answer these two questions and briefly explain your answers using 2 of Newton’s 3 laws of motion.

59. Two satellites of equal mass (1.6 x 103 kg) are put into orbit 30 m apart. What is the magnitude of the gravitational force between them? (2.0 x 10-7 N.)

60. The force of gravity between two objects is 81 N. What happens to that force if the distance between them

increases?

a. What happens to the force is the product of their masses decreases?

61. How is mass related to the force of gravity?

62. How is distance related to the force of gravity?

Impulse, Momentum, Conservation of Momentum

63. Define the Law of Conservation of Momentum (COP).

64. If you toss an egg up in the air and then catch it, no matter how you catch it the egg will go from a high momentum

to zero momentum. And yet, the egg can either break in your hand or not, depending on how you catch it. Explain

how this is possible by analyzing the Impulse-Momentum Theorem equation: Ft = m(vf – vi)

65. What is the momentum of an 85kg football player, running at 9.0 m/s? (765 kg·m/s)

66. A 6500-kg freight car traveling at 2.5 m/s collides with an 800-kg stationary freight car. If they stick together upon

collision, find their velocity. (2.2 m/s)

Energy, Work & Power

67. Determine if work is done in the following scenarios. Why or why not?

a. A teacher carries a chair around the room

b. You lift a book off the ground

c. You apply brakes slowing down your car

d. Holding a newborn baby for a photo

e. A comet traveling through space

68. What are the 2 definitions of work that I’ve given you so far?

69. The Titan’s mass is 750 kg. When it is 30 m off the ground it is moving at a speed of 35 m/s. Neglecting the effect of

friction, calculate its gravitational potential energy, and kinetic energy at this point. (220,500 J; 459,375 J)

70. What is the mass of a book held 2.2 m above the floor with 220 J of potential energy? [10.2 kg]

71. Calculate the kinetic energy of a 2.2 kg dog running at a speed of 22 m/s. [532.4 J]

72. How much work is done if you raise a 90 kg crate 1.5 m above the ground? (1323 J)

a. What was your power if you did this in 5.5 sec? (240.5 W)

b. Name 3 ways you could DECREASE your power in this lift.

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