Physics Chapter 6 WORKsheets

1. A man pushes a crate across the floor by applying a force of 250 N. The crate move at a constant velocity and travels 12.75 m.

A. How much work does the man do? B. How much work does friction do? C. How much work does gravity do?

A. +3190 J B. -3190 J

C. 0 J

2. How much work is required to lift 136 kg to a height of 1.2 m at a constant speed? A. How much work does gravity do on the weight?

1.2 m

+1600 J A. -1600 J

3. A force of 50.0 N is applied at an angle of 37° to a sled whose mass is 50.0 kg. The sled is pulled 8.0 m and the coefficient of

friction is 0.07. A. How much work is done on the sled by the applied force? B. How much work is done on the sled by the friction force? C. What is the net work done on the sled? D. Will the sled speed up? Slow down? Travel with a constant velocity?

A. +319. J B. –274 J C. +45 J D. Speed up

4. A snickers bar contains 1,172,000 J (280 kcal) of energy. How many flights of stairs (each floor is 3.65 m) does a 84.0 kg

person have to climb in order to “burn up” 1 snickers bar?

390 flights

5. A student is out walking his dog. The dog sees a cat and begins dragging the 75.0 kg student with a force of 250.0 N across a

frictionless field. The dog does 1375 J of work. How far does the dog drag the student?

5.5 m

6. A force of 150.0 N is applied to a sled whose mass is 50.0 kg. The sled is pulled 8.0 m and the coefficient of friction is 0.10. A. How much work is done on the sled by the applied force? B. How much work is done on the sled by the friction force? C. What is the net work done on the sled? D. What is the work done by gravity on the sled?

A. +1200. J B. –392 J C. +808 J D. 0 J

7. Six books, each is 0.05 m thick and has a mass of 1.4 kg are lying flat on a table. How much work is required to stack them

one on top of another?

PHYSICS PHYSICS PHYSICS PHYSICS PHYSICS

PHYSICS

10.3 J 8. A 5.0 kg box is accelerated from rest across a frictionless floor at 2.0 m/s2 for 5.0 seconds.

A. How far will the box move? B. How much work was done on the box?

A. 25 m B. 250 J

9. The crate below is pulled a distance of 5.0 meters by the force P. If the floor is frictionless and the force does 1732 J of

work, what is the angle θ?

θ

30°

10. State whether the work done by force F in the following situations is (+positive, - negative, or 0 zero)

F moves

F movesmoves

F

moves

moves

F F

moves

F

11. A force of 150.0 N is applied to a cart whose mass is 40.0 kg. The cart is pulled 10.0 m and the coefficient of friction is 0.20.

A. How much work is done on the cart by the applied force? B. How much work is done on the cart by the friction force? C. What is the net work done on the cart? D. What is the work done by gravity on the cart?

150 N

A. +1500. J B. – 784 J C. + 716 J D. 0 J

12. How much work does gravity do on the 2 kg vase as it falls?

3 m

[60 J]

13. While climbing Mt. Pioneer, Mr. McGeechan lifts his massively jacked 90 kg body up. In doing so he does 4,500 J of work.

How high up did he climb?

???

[5 m]

14. Four books, each is 0.05 m thick and has a mass of 1.5 kg are lying flat on a table. Which book would require the most amount of work to stack? The least? How much work is required to stack them one on top of another?

[4.5 J]

15. Eight books, each with mass 1.7 kg, lie flat on a table. If it takes 20.1 J to stack the books, how thick is each book?

[0.043 m]

16. A 1300-N crate rests on the floor. How much work is required to move it at constant speed (a) 4.0 m along the floor against a friction force of 230 N, and [920 J] (b) 4.0 m vertically? [5200 J]

17. If the human body could convert a candy bar directly into work how high could an 82-kg man climb a ladder if he were

fueled by one bar (= 1100 kJ)?

[1370 m]

18. The coefficient of kinetic friction between a suitcase and the floor is 0.26. If the suitcase has a mass of 70.0 kg, how far can it be pushed across the level floor with 640 J of work?

[3.6 m]

19. A water skier is being towed behind a boat. The boat does 10,000 J of work on the skier and the tension in the rope is 380 N.

What angle does the rope make if the skier moves 30 m? [28.7°]

30 mθ

20. A 64 kg student travels a height of 15 m. a. What amount of work is required? [9408 J] b. If the student produced 480 W of power, how long did the trip take? [19.6 s]

21. If an engine does 1500 J of work in 2.0 minutes, what is its power in Watts? [12.5 W]

22. A motorized winch is rated at 10.0 kW. What maximum constant speed can this winch raise a mass of 27,500 kg? [0.037

m/s]

23. A 250 W motor must do a job that requires 145,000 J. How long will it take to do this job? [580 s]

24. Playing basketball requires 800 W of power. How much work is done in 12 min of basketball? [576 kJ]

25. Sleeping requires 83 W of power. How long in hours would you have to sleep to burn 1,172,000 J of energy (1 Snickers

bar)? [3.92 hours!]

26. How much power is required to bench press 136 kg (300 lbs) to a height of 0.45 m if it takes 0.20 seconds to lift? [3000 W]

27. A bulldozer pushes a rock with a force of 8500 N at 1.8 m/s for 35 s. a. How far does the rock travel? [63 m] b. How much work is done by the bulldozer? [535,500 J] c. How much power is required? [15,300 W]

Work and Graphing. SPRING GRAPHS (HOOKE’S LAW

0

10

20

30

40

50

60

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Distance (m)

Forc

e (N

)

28. What is the spring constant (k) of the spring?

[40 N/m] 29. How much work is required to stretch the spring from 0 to 1.4 m?

[39.2 J]

0

10

20

30

40

50

60

70

80

90

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Distance (m)

Forc

e (N

)

SPRING A SPRING B SPRING C

30. Rank the springs from largest to smallest spring constant.

31. How much work is needed to stretch spring B from 0.5 m to 0.9 m?

[10 J]

32. Given the following graph, determine the work done by the force.

[24 J]

33. Given the following graph, determine the work done by the force.

[30 J]

KINETIC ENERGY

Just Kinetic

34. What is the kinetic energy of a 0.500 kg baseball traveling at 25.0 m/s?

[156 J] 35. What will be the kinetic energy of the baseball in problem #34 if its velocity is tripled?

[1406 J]

36. A 3.5 kg object has a kinetic energy of 2400 J. How fast is it traveling?

[37 m/s]

37. 6500 J of kinetic energy is given to a ball. As a result it travels at 15 m/s. What is its mass?

[58 kg]

38. A 10 kg toy car is traveling at 4 m/s. It increases its velocity by 15%. A. What is its new velocity? [4.6 m/s] B. By how much (%) does its kinetic energy increase? [32%]

39. An 65 kg athlete on a trampoline leaps straight up into the air with an initial speed of 9.0 m/s. What is the kinetic energy?

[2633 J] 40. A 70-kg base runner begins his slide into second base when he is moving at a speed of 4.0 m/s. What is his kinetic energy?

[560 J] 41. A 7.00 kg bowling ball moves at 3.00 m/s. How fast must a 2.45 gram Ping-Pong ball move so that the two balls have the

same kinetic energy

[160 m/s]

42. A 0.60-kg particle has a speed of 2.0 m/s at point A and a kinetic energy of 7.5 J at point B. What is

(a) its kinetic energy at A? [1.2 J] (b) its speed at point B? [5 m/s]

43. What happens to the kinetic energy of an object if its velocity is tripled? Its mass is tripled? Its velocity is quadrupled?

44. Can an object have negative kinetic energy? Explain…

45. A car going 5 m/s increases its velocity to 7 m/s. How much will its kinetic energy increase?

[by 24 J] 46. A ball going 6 m/s has a kinetic energy of 450 J. What is the mass of the ball?

[25 kg]

Just Potential

47. What is the potential energy of the 85 kg skier that is 5 m above the bottom of a hill?

[4165 J] 48. How high would a 3.9 kg ball have to be in order to have 345 J of potential energy?

[9 m] 49. A rock on top of an 8 m tall hill has 380 J of potential energy. What must be the mass of the rock?

[4.85 kg] 50. How much potential energy will a spring (k = 48 N/m) have if it is compressed 0.85 m?

[17.3 J]

51. What is the spring constant of a spring that stores 1150 J on energy when it is compressed 75 cm?

[4089 N/m] 52. How far do you have to pull a spring (k = 125 N/m) in order for it to store 600 J of energy?

[3.1 m] 53. How much energy does a spring (k = 345 N/m) store if it is stretched 0.55 m? If all that energy were given to a 3.0 kg car

what would its velocity be?

[52.1 J, 5.9 m/s]

54. What is the potential energy of the 80 kg skier:

(a) A t point A? [7840 J] (b) At point B? [0 J] (c) What is her kinetic energy at point B? [7840 J]

0.5 m 55. The block is pushed up against the spring and is held at rest. A. How much PE does it have initially? [11.9 J] B. How much PE will it have when the spring lets go? [0 J]

k = 95 N/m C. What is its KE initially? [0 J] 2 kg D. What is its KE after the spring lets go? [11.9 J]

E. How fast will it be traveling after the spring lets go? [3.4 m/s]

56. What is the potential energy of the block in each situation:

5 m

3 kg

40º

10 m

5 kg 4 m [315 J]

[88.2 J]

30º

4 kg

7 m

[158 J]

Conservation of Energy WITH GRAVITY

PE:_____________ KE:____________ Tot. E:__________

60 kg 57. Fill in the blanks:

v = 0

15 m

PE:_____________ KE:____________ Tot. E:__________

58. Fill in the blanks

PE:_____________ KE:____________ Tot. E:__________

60 kg v = 5 m/s

PE:_____________ KE:____________ Tot. E:__________

20 m

PE:_____________ KE:____________ Tot. E:__________

59. Fill in the blanks

v = 30 m/s

3 kg

PE:_____________ KE:____________ Tot. E:__________

Velocity of sled at bottom in #57________Velocity of sled at bottom #58___________Velocity of rocket at top #59__________ WITH SPRINGS

60. Fill in the blanks PE:_____________ KE:____________ Tot. E:__________

k = 450 N/m

3 kg

0.5 m

PE:_____________ KE:____________ Tot. E:__________

3 kg

61. You know the deal…. 10 kg

PE:_____________ KE:____________ Tot. E:__________

v = 0

k = 900 N/m (stops after hitting spring)

4 m

PE:_____________ KE:____________ Tot. E:__________

62. You know the deal…..

PE:_____________ KE:____________ Tot. E:__________

d = 0.2 m

m = 1 kg

PE:_____________ KE:____________ Tot. E:__________

v = 3 m/s

2 m

Velocity of the block in #60_________Distance (d) spring compresses in #61___________Spring constant (k) in #62____________

63. What is the μ in the following situation? (Starts and ends at rest)

[μ = 0.33]

64. What will be the speed at B? At C? How far into the friction will it travel? hmm…no mass is given

3 m/s

11 m

μ = 0.45 5 m

[vB = 15 m/s, vC = 11.3 m/s, d = 14.3 m]

65. By how much will the spring compress if μ = 0.15 on the level surface?

1.5 m

[0.83 m] For all problems….Snoopy’s mass is 55 kg

66. How far will Snoop travel in the following situation? v = 0 3 m

?

K = 1120 N/m μ = 0.55

[17 m]

67. How high up the other side of the half pipe will Snoop go ?

h = ? [12 m]

µ = 0.18

2.5 m

12 m

v0 = 3 m/s

How fast will Snoop be going after he exits the rough surface?

[15.3 m/s] How far from the stop sign will he come to rest (no energy)?

[0.78 m]

68. The 10 kg block is released from rest at point A. There is only friction between points B and C. The block hits the spring and

causes it to compress 0.30 m. A. What is the coefficient of friction between B and C? B. How far from point B will the block come to rest with no energy?

k = 2,250 N/m

[A. μ = 0.33] [B. 2.9 m]