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Chapter 5 - 8 Review



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

1. 

A force does work on an object if a component of the force
a.
is perpendicular to the displacement of the object.
b.
is parallel to the displacement of the object.
c.
perpendicular to the displacement of the object moves the object along a path that returns the object to its starting position.
d.
parallel to the displacement of the object moves the object along a path that returns the object to its starting position.
 

2. 

Work is done when
a.
the displacement is not zero.
b.
the displacement is zero.
c.
the force is zero.
d.
the force and displacement are perpendicular.
 

3. 

A 1.00 ´ 103 kg sports car accelerates from rest to 25.0 m/s in 7.50 s. What is the average power output of the automobile engine?
a.
20.8 kW
c.
41.7 kW
b.
30.3 kW
d.
52.4 kW
 

4. 

The magnitude of the component of the force that does the work is 43.0 N. How much work is done on a bookshelf being pulled 5.00 m at an angle of 37.0° from the horizontal?
a.
172 J
c.
129 J
b.
215 J
d.
792 J
 

5. 

A worker pushes a wheelbarrow with a horizontal force of 50.0 N over a level distance of 5.0 m. If a frictional force of 43 N acts on the wheelbarrow in a direction opposite to that of the worker, what net work is done on the wheelbarrow?
a.
250 J
c.
35 J
b.
0.0 J
d.
10.0 J
 

6. 

A hill is 100 m long and makes an angle of 12° with the horizontal. As a 50 kg jogger runs up the hill, how much work does gravity do on the jogger?
a.
50 000 J
c.
–10 000 J
b.
10 000 J
d.
0.0 J
 

7. 

A child moving at constant velocity carries a 2 N ice-cream cone 1 m across a level surface. What is the net work done on the ice-cream cone?
a.
0 J
c.
2 J
b.
0.5 J
d.
20 J
 

8. 

A construction worker pushes a wheelbarrow 5.0 m with a horizontal force of 50.0 N. How much work is done by the worker on the wheelbarrow?
a.
10 J
c.
250 J
b.
1250 J
d.
55 J
 

9. 

A horizontal force of 200 N is applied to move a 55 kg television set across a 10 m level surface. What is the work done by the 200 N force on the television set?
a.
4000 J
c.
2000 J
b.
5000 J
d.
6000 J
 

10. 

A flight attendant pulls a 50.0 N flight bag a distance of 250.0 m along a level airport floor at a constant speed. A 30.0 N force is exerted on the bag at an angle of 50.0° above the horizontal. How much work is done on the flight bag?
a.
12 500 J
c.
4820 J
b.
7510 J
d.
8040 J
 

11. 

Which of the following energy forms is involved in winding a pocket watch?
a.
electrical energy
c.
gravitational potential energy
b.
nonmechanical energy
d.
elastic potential energy
 

12. 

Which of the following energy forms is NOT involved in hitting a tennis ball?
a.
kinetic energy
c.
gravitational potential energy
b.
chemical potential energy
d.
elastic potential energy
 

13. 

A 3.00 kg toy falls from a height of 10.0 m. Just before hitting the ground, what will be its kinetic energy? (Disregard air resistance. g = 9.81 m/s2.)
a.
98.0 J
c.
29.4 J
b.
0.98 J
d.
294 J
 

14. 

If the only force acting on an object is friction during a given physical process, which of the following assumptions must be made in regard to the object’s kinetic energy?
a.
The kinetic energy decreases.
b.
The kinetic energy increases.
c.
The kinetic energy remains constant.
d.
The kinetic energy decreases and then increases.
 

15. 

What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
a.
54.0 J
c.
108 J
b.
87.0 J
d.
216 J
 

16. 

If both the mass and the velocity of a ball are tripled, the kinetic energy of the ball is increased by a factor of
a.
3.
c.
9.
b.
6.
d.
27.
 

17. 

Which of the following energy forms is associated with an object in motion?
a.
potential energy
c.
nonmechanical energy
b.
elastic potential energy
d.
kinetic energy
 

18. 

Which of the following energy forms is associated with an object due to its position?
a.
potential
c.
total
b.
positional
d.
kinetic
 

19. 

The main difference between kinetic energy and potential energy is that
a.
kinetic energy involves position and potential energy involves motion.
b.
kinetic energy involves motion and potential energy involves position.
c.
although both energies involve motion, only kinetic involves position.
d.
although both energies involve position, only potential involves motion.
 

20. 

Which of the following energy forms is associated with an object due to its position relative to Earth?
a.
potential energy
c.
gravitational potential energy
b.
elastic potential energy
d.
kinetic energy
 

21. 

Which of the following energy forms is stored in any compressed or stretched object?
a.
nonmechanical energy
c.
gravitational potential energy
b.
elastic potential energy
d.
kinetic energy
 

22. 

The equation for determining gravitational potential energy is PEg = mgh. Which factor(s) in this equation is (are) NOT a property of an object?
a.
g
c.
m
b.
h
d.
both g and h
 

23. 

Which form of energy is involved in weighing fruit on a spring scale?
a.
kinetic energy
c.
gravitational potential energy
b.
nonmechanical energy
d.
elastic potential energy
 

24. 

As an object is lowered into a deep hole in the ground, which of the following assumptions must be made in regard to the object’s potential energy?
a.
The potential energy increases.
b.
The potential energy decreases.
c.
The potential energy remains constant.
d.
The potential energy increases and then decreases.
 

25. 

A 40.0 N crate is pulled up a 5.0 m inclined plane at a constant velocity. If the plane is inclined at an angle of 37° to the horizontal and there is a constant force of friction of 10.0 N between the crate and the surface, what is the net gain in potential energy by the crate?
a.
120 J
c.
210 J
b.
–120 J
d.
–210 J
 

26. 

A 0.002 kg coin, which has zero potential energy at rest, is dropped into a 10.0 m well. After the coin comes to a stop in the mud, what is its potential energy?
a.
0.000 J
c.
–0.196 J
b.
0.196 J
d.
0.020 J
 

27. 

A 5.00 ´ 102 N crate is at the top of a 5.00 m ramp, which is inclined at 20.0° with the horizontal. What is its potential energy? (g = 9.81 m/s2.)
a.
855 J
c.
815 J
b.
2350 J
d.
8390 J
 

28. 

Why doesn’t the principle of mechanical energy conservation hold in situations when frictional forces are present?
a.
Kinetic energy is not simply converted to a form of potential energy.
b.
Potential energy is simply converted to a form of gravitational energy.
c.
Chemical energy is not simply converted to electrical energy.
d.
Kinetic energy is simply converted to a form of gravitational energy.
 

29. 

A 16.0 kg child on roller skates, initially at rest, rolls 2.0 m down an incline at an angle of 20.0° with the horizontal. If there is no friction between incline and skates, what is the kinetic energy of the child at the bottom of the incline? (g = 9.81 m/s2.)
a.
210 J
c.
11 J
b.
610 J
d.
110 J
 

30. 

A pole vaulter clears 6.00 m. With what velocity does the vaulter strike the mat in the landing area? (Disregard air resistance. g = 9.81 m/s2.)
a.
2.70 m/s
c.
10.8 m/s
b.
5.40 m/s
d.
21.6 m/s
 

31. 

A bobsled zips down an ice track starting at 150 m vertical distance up the hill. Disregarding friction, what is the velocity of the bobsled at the bottom of the hill?
(g = 9.81 m/s2.)
a.
27 m/s
c.
45 m/s
b.
36 m/s
d.
54 m/s
 

32. 

A professional skier starts from rest and reaches a speed of 56 m/s on a ski slope 30.0° above the horizontal. Using the work–kinetic energy theorem and disregarding friction, find the minimum distance along the slope the skier would have to travel in order to reach this speed.
a.
110 m
c.
320 m
b.
160 m
d.
640 m
 

33. 

A 40.0 N crate starting at rest slides down a rough 6.0 m long ramp inclined at 30.0° with the horizontal. The force of friction between the crate and ramp is 6.0 N. Using the work–kinetic energy theorem, find the velocity of the crate at the bottom of the incline.
a.
8.7 m/s
c.
4.5 m/s
b.
3.3 m/s
d.
6.4 m/s
 

34. 

A 15.0 kg crate, initially at rest, slides down a ramp 2.0 m long and inclined at an angle of 20.0° with the horizontal. Using the work–kinetic energy theorem and disregarding friction, find the velocity of the crate at the bottom of the ramp. (g = 9.81 m/s2.)
a.
6.1 m/s
c.
9.7 m/s
b.
3.7 m/s
d.
8.3 m/s
 

35. 

A parachutist with a mass of 50.0 kg jumps out of an airplane at an altitude of 1.00 ´ 103 m. After the parachute deploys, the parachutist lands with a velocity of 5.00 m/s. Using the work–kinetic energy theorem, find the energy that was lost to air resistance during this jump. (g = 9.81 m/s2.)
a.
49 300 J
c.
198 000 J
b.
98 800 J
d.
489 000 J
 

36. 

A horizontal force of 2.00 ´ 102 N is applied to a 55.0 kg cart across a 10.0 m level surface, accelerating it 2.00 m/s2. Using the work–kinetic energy theorem, find the force of friction that slows the motion of the cart? (Disregard air resistance. g = 9.81 m/s2.)
a.
110 N
c.
80.0 N
b.
90.0 N
d.
70.0 N
 

37. 

Which of the following is the rate at which energy is transferred?
a.
potential energy
c.
mechanical energy
b.
kinetic energy
d.
power
 

38. 

Which of the following equations is NOT an equation for power?
a.
ch4-8_review_files/i0390000.jpg
c.
ch4-8_review_files/i0390001.jpg
b.
ch4-8_review_files/i0390002.jpg
d.
ch4-8_review_files/i0390003.jpg
 

39. 

What is the average power supplied by a 60.0 kg secretary running up a flight of stairs rising vertically 4.0 m in 4.2 s?
a.
380 W
c.
610 W
b.
560 W
d.
670 W
 

40. 

What is the average power output of a weight lifter who can lift 250 kg 2.0 m in 2.0 s?
a.
5.0 ´ 102 W
c.
4.9 kW
b.
2.5 kW
d.
9.8 kW
 

41. 

Water flows over a section of Niagara Falls at a rate of 1.20 ´ 106 kg/s and falls 50.0 m. What is the power of the waterfall?
a.
589 MW
c.
147 MW
b.
294 MW
d.
60.0 MW
 

42. 

Which of the following has the greatest momentum?
a.
truck with a mass of 2250 kg moving at a velocity of 25 m/s
b.
car with a mass of 1210 kg moving at a velocity of 51 m/s
c.
truck with a mass of 6120 kg moving at a velocity of 10 m/s
d.
car with a mass of 1540 kg moving at a velocity of 38 m/s
 

43. 

Which of the following has the greatest momentum?
a.
tortoise with a mass of 270 kg moving at a velocity of 0.5 m/s
b.
hare with a mass of 2.7 kg moving at a velocity of 7 m/s
c.
turtle with a mass of 91 kg moving at a velocity of 1.4 m/s
d.
roadrunner with a mass of 1.8 kg moving at a velocity of 6.7 m/s
 

44. 

What velocity must a 1340 kg car have in order to have the same momentum as a 2680 kg truck traveling at a velocity of 15 m/s to the west?
a.
6.0 ´ 101 m/s to the west
c.
3.0 ´ 101 m/s to the west
b.
6.0 ´ 101 m/s to the east
d.
3.0 ´ 101 m/s to the east
 

45. 

A child with a mass of 23 kg rides a bike with a mass of 5.5 kg at a velocity of 4.5 m/s to the south. Compare the momentum of the child with the momentum of the bike.
a.
Both the child and the bike have the same momentum.
b.
The bike has a greater momentum than the child.
c.
The child has a greater momentum than the bike.
d.
Neither the child nor the bike has momentum.
 

46. 

When comparing the momentum of two moving objects, which of the following is correct?
a.
The object with the higher velocity will have less momentum if the masses are equal.
b.
The more massive object will have less momentum if its velocity is greater.
c.
The less massive object will have less momentum if the velocities are the same.
d.
The more massive object will have less momentum if the velocities are the same.
 

47. 

A baseball is pitched very fast. Another baseball of equal mass is pitched very slowly. Which of the following statements is correct?
a.
The fast-moving baseball is harder to stop because it has more momentum.
b.
The slow-moving baseball is harder to stop because it has more momentum.
c.
The fast-moving baseball is easier to stop because it has more momentum.
d.
The slow-moving baseball is easier to stop because it has more momentum.
 

48. 

A roller coaster climbs up a hill at 4 m/s and then zips down the hill at 30 m/s. The momentum of the roller coaster
a.
is greater up the hill than down the hill.
c.
remains the same throughout the ride.
b.
is greater down the hill than up the hill.
d.
is zero throughout the ride.
 

49. 

A person sitting in a chair with wheels stands, causing the chair to roll backward across the floor. The momentum of the chair
a.
was zero while stationary and increased when the person stood.
b.
was greatest while the person sat in the chair.
c.
remained the same.
d.
was zero when the person got out of the chair and increased while the person sat.
 

50. 

A student walks to class at a velocity of 3 m/s. To avoid walking into a door as it opens, the student slows to a velocity of 0.5 m/s. Now late for class, the student runs down the corridor at a velocity of 7 m/s. The student had the least momentum
a.
while walking at a velocity of 3 m/s.
b.
while dodging the opening door.
c.
immediately after the door opened.
d.
while running to class at a velocity of 7 m/s.
 

51. 

An ice skater initially skating at a velocity of 3 m/s speeds up to a velocity of 5 m/s. The momentum of the skater
a.
decreases.
c.
remains the same.
b.
increases.
d.
becomes zero.
 

52. 

If a force is exerted on an object, which statement is true?
a.
A large force always produces a large change in the object’s momentum.
b.
A large force produces a large change in the object’s momentum only if the force is applied over a very short time interval.
c.
A small force applied over a long time interval can produce a large change in the object’s momentum.
d.
A small force produces a large change in the object’s momentum.
 

53. 

The change in an object’s momentum is equal to
a.
the product of the mass of the object and the time interval.
b.
the product of the force applied to the object and the time interval.
c.
the time interval divided by the net external force.
d.
the net external force divided by the time interval.
 

54. 

A force is applied to stop a moving shopping cart. Increasing the time interval over which the force is applied
a.
requires a greater force.
c.
requires a smaller force.
b.
has no effect on the force needed.
d.
requires the same force.
 

55. 

Which of the following situations is an example of a visible change in momentum?
a.
A hiker walks through a spider’s web.
c.
A volleyball hits a mosquito in the air.
b.
A car drives over a pebble.
d.
A baseball is hit by a bat.
 

56. 

Which of the following situations is an example of change in momentum?
a.
A tennis ball is hit into a net.
b.
A helium-filled balloon rises upward into the sky.
c.
An airplane flies into some scattered white clouds.
d.
A bicyclist rides over a leaf on the pavement.
 

57. 

A 6.0 ´ 10–2 kg tennis ball moves at a velocity of 12 m/s. The ball is struck by a racket, causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in the ball’s momentum?
a.
–0.38 kg·m/s
c.
–1.1 kg·m/s
b.
–0.72 kg·m/s
d.
–1.8 kg·m/s
 

58. 

A rubber ball with a mass of 0.30 kg is dropped onto a steel plate. The ball’s velocity just before impact is 4.5 m/s and just after impact is 4.2 m/s. What is the change in the ball’s momentum?
a.
–0.09 kg·m/s
c.
–4.0 kg·m/s
b.
–2.6 kg·m/s
d.
–12 kg·m/s
 

59. 

A ball with a momentum of 4.0 kg·m/s hits a wall and bounces straight back without losing any kinetic energy. What is the change in the ball’s momentum?
a.
0.0 kg·m/s
c.
8.0 kg·m/s
b.
–4.0 kg·m/s
d.
–8.0 kg·m/s
 

60. 

A ball with a mass of 0.15 kg and a velocity of 5.0 m/s strikes a wall and bounces straight back with a velocity of 3.0 m/s. What is the change in momentum of the ball?
a.
–0.30 kg·m/s
c.
–0.15 kg·m/s
b.
–1.20 kg·m/s
d.
–7.50 kg·m/s
 

61. 

The impulse experienced by a body is equivalent to the body’s change in
a.
velocity.
c.
momentum.
b.
kinetic energy.
d.
force.
 

62. 

A moderate force will break an egg. However, an egg dropped on the road usually breaks, while one dropped on the grass usually does not break because for the egg dropped on the grass,
a.
the change in momentum is greater.
c.
the time interval for stopping is greater.
b.
the change in momentum is less.
d.
the time interval for stopping is less.
 

63. 

Which of the following statements properly relates the variables in the equation FDt = Dp?
a.
A large constant force changes an object’s momentum over a long time interval.
b.
A large constant force acting over a long time interval causes a large change in momentum.
c.
A large constant force changes an object’s momentum at various time intervals.
d.
A large constant force does not necessarily cause a change in an object’s momentum.
 

64. 

A large moving ball collides with a small stationary ball. The momentum
a.
of the large ball decreases, and the momentum of the small ball increases.
b.
of the small ball decreases, and the momentum of the large ball increases.
c.
of the large ball increases, and the momentum of the small ball decreases.
d.
does not change for either ball.
 

65. 

A rubber ball moving at a speed of 5 m/s hit a flat wall and returned to the thrower at 5 m/s. The magnitude of the momentum of the rubber ball
a.
increased.
c.
remained the same.
b.
decreased.
d.
was not conserved.
 

66. 

Two objects with different masses collide and bounce back after an elastic collision. Before the collision, the two objects were moving at velocities equal in magnitude but opposite in direction. After the collision,
a.
the less massive object had gained momentum.
b.
the more massive object had gained momentum.
c.
both objects had the same momentum.
d.
both objects lost momentum.
 

67. 

Two skaters stand facing each other. One skater’s mass is 60 kg, and the other’s mass is 72 kg. If the skaters push away from each other without spinning,
a.
the 60 kg skater travels at a lower momentum.
b.
their momenta are equal but opposite.
c.
their total momentum doubles.
d.
their total momentum decreases.
 

68. 

Two swimmers relax close together on air mattresses in a pool. One swimmer’s mass is 48 kg, and the other’s mass is 55 kg. If the swimmers push away from each other,
a.
their total momentum triples.
c.
their total momentum doubles.
b.
their momenta are equal but opposite.
d.
their total momentum decreases.
 

69. 

A soccer ball collides with another soccer ball at rest. The total momentum of the balls
a.
is zero.
c.
remains constant.
b.
increases.
d.
decreases.
 

70. 

In a two-body collision,
a.
momentum is conserved.
b.
kinetic energy is conserved.
c.
neither momentum nor kinetic energy is conserved.
d.
both momentum and kinetic energy are conserved.
 

71. 

The law of conservation of momentum states that
a.
the total initial momentum of all objects interacting with one another usually equals the total final momentum.
b.
the total initial momentum of all objects interacting with one another does not equal the total final momentum.
c.
the total momentum of all objects interacting with one another is zero.
d.
the total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects.
 

72. 

Which of the following statements about the conservation of momentum is NOT correct?
a.
Momentum is conserved for a system of objects pushing away from each other.
b.
Momentum is not conserved for a system of objects in a head-on collision.
c.
Momentum is conserved when two or more interacting objects push away from each other.
d.
The total momentum of a system of interacting objects remains constant regardless of forces between the objects.
 

73. 

A swimmer with a mass of 75 kg dives off a raft with a mass of 500 kg. If the swimmer’s speed is 4 m/s immediately after leaving the raft, what is the speed of the raft?
a.
0.2 m/s
c.
0.6 m/s
b.
0.5 m/s
d.
4.0 m/s
 

74. 

A bullet with a mass of 5.00 ´ 10–3 kg is loaded into a gun. The loaded gun has a mass of 0.52 kg. The bullet is fired, causing the empty gun to recoil at a speed of 2.1 m/s. What is the speed of the bullet?
a.
48 m/s
c.
120 m/s
b.
220 m/s
d.
360 m/s
 

75. 

A 65.0 kg ice skater standing on frictionless ice throws a 0.15 kg snowball horizontally at a speed of 32.0 m/s. At what velocity does the skater move backward?
a.
0.07 m/s
c.
0.15 m/s
b.
0.30 m/s
d.
1.20 m/s
 

76. 

Two skaters, each with a mass of 50 kg, are stationary on a frictionless ice pond. One skater throws a 0.2 kg ball at 5 m/s to the other skater, who catches it. What are the velocities of the skaters when the ball is caught?
a.
0.02 m/s moving apart
c.
0.02 m/s moving toward each other
b.
0.04 m/s moving apart
d.
0.04 m/s moving toward each other
 

77. 

Two carts with masses of 1.5 kg and 0.7 kg, respectively, are held together by a compressed spring. When released, the 1.5 kg cart moves to the left with a velocity of 7 m/s. What is the velocity of the 0.7 kg cart? (Disregard the mass of the spring.)
a.
15 m/s to the right
c.
7 m/s to the right
b.
15 m/s to the left
d.
7 m/s to the left
 

78. 

Each croquet ball in a set has a mass of 0.50 kg. The green ball travels at 10.5 m/s and strikes a stationary red ball. If the green ball stops moving, what is the final speed of the red ball after the collision?
a.
10.5 m/s
c.
12.0 m/s
b.
6.0 m/s
d.
9.6 m/s
 

79. 

A diver with a mass of 80.0 kg jumps from a dock into a 130.0 kg boat at rest on the west side of the dock. If the velocity of the diver in the air is 4.10 m/s to the west, what is the final velocity of the diver after landing in the boat?
a.
2.52 m/s to the west
c.
1.56 m/s to the west
b.
2.52 m/s to the east
d.
1.56 m/s to the east
 

80. 

Two objects move separately after colliding, and both the total momentum and total kinetic energy remain constant. Identify the type of collision.
a.
elastic
c.
inelastic
b.
perfectly elastic
d.
perfectly inelastic
 

81. 

Two objects stick together and move with the same velocity after colliding. Identify the type of collision.
a.
elastic
c.
inelastic
b.
perfectly elastic
d.
perfectly inelastic
 

82. 

After colliding, objects are deformed and lose some kinetic energy. Identify the type of collision.
a.
elastic
c.
inelastic
b.
perfectly elastic
d.
perfectly inelastic
 

83. 

Two balls of dough collide and stick together. Identify the type of collision.
a.
elastic
c.
inelastic
b.
perfectly elastic
d.
perfectly inelastic
 

84. 

Two snowballs with masses of 0.40 kg and 0.60 kg, respectively, collide head-on and combine to form a single snowball. The initial speed for each is 15 m/s. If the velocity of the snowball with a mass of 1.0 kg is 3.0 m/s after the collision, what is the decrease in kinetic energy?
a.
zero
c.
60 J
b.
110 J
d.
90 J
 

85. 

A 1.5 ´ 103 kg truck moving at 15 m/s strikes a 7.5 ´ 102 kg automobile stopped at a traffic light. The vehicles hook bumpers and skid together at 10.0 m/s. What is the decrease in kinetic energy?
a.
1.1 ´ 105 J
c.
1.7 ´ 105 J
b.
1.2 ´ 104 J
d.
6.0 ´ 104 J
 

86. 

A clay ball with a mass of 0.35 kg has an initial speed of 4.2 m/s. It strikes a 3.5 kg clay ball at rest, and the two balls stick together and remain stationary. What is the decrease in kinetic energy of the 0.35 kg ball?
a.
1.6 J
c.
3.1 J
b.
4.8 J
d.
6.4 J
 

87. 

An infant throws 5 g of applesauce at a velocity of 0.2 m/s. All of the applesauce collides with a nearby wall and sticks. What is the decrease in kinetic energy of the applesauce?
a.
2 ´ 10–4 J
c.
1 ´ 10–3 J
b.
0.5 ´ 10–4 J
d.
1 ´ 10–4 J
 

88. 

In an elastic collision between two objects with unequal masses,
a.
the total momentum of the system will increase.
b.
the total momentum of the system will decrease.
c.
the kinetic energy of one object will increase by the amount that the kinetic energy of the other object decreases.
d.
the momentum of one object will increase by the amount that the momentum of the other object decreases.
 

89. 

A billiard ball collides with a stationary identical billiard ball in an elastic head-on collision. After the collision, which is true of the first ball?
a.
It maintains its initial velocity.
c.
It comes to rest.
b.
It has one-half its initial velocity.
d.
It moves in the opposite direction.
 

90. 

A billiard ball collides with a second identical ball in an elastic head-on collision. What is the kinetic energy of the system after the collision compared with the kinetic energy before the collision?
a.
unchanged
c.
two times as great
b.
one-fourth as great
d.
four times as great
 

91. 

Which of the following best describes the kinetic energy of each object after a two-body collision if the momentum of the system is conserved?
a.
must be less
c.
might also be conserved
b.
must also be conserved
d.
is doubled in value
 

92. 

Which of the following best describes the momenta of two bodies after a two-body collision if the kinetic energy of the system is conserved?
a.
must be less
c.
might also be conserved
b.
must also be conserved
d.
is doubled in value
 

93. 

An object with a mass of 0.10 kg makes an elastic head-on collision with a stationary object with a mass of 0.15 kg. The final velocity of the 0.10 kg object after the collision is –0.045 m/s and the final velocity of the 0.15 kg object after the collision is 0.16 m/s. What was the initial velocity of the 0.10 kg object?
a.
0.16 m/s
c.
0.20 m/s
b.
–1.06 m/s
d.
–0.20 m/s
 

94. 

A 90 kg halfback runs north and is tackled by a 120 kg opponent running south at 4 m/s. The collision is perfectly inelastic. Just after the tackle, both players move at a velocity of 2 m/s north. Calculate the velocity of the 90 kg player just before the tackle.
a.
3 m/s south
c.
10 m/s north
b.
4 m/s south
d.
12 m/s north
 

95. 

A clay ball with a mass of 0.35 kg strikes another 0.35 kg clay ball at rest, and the two balls stick together. The final velocity of the balls is 2.1 m/s north. What was the first ball’s initial velocity?
a.
4.2 m/s to the north
c.
2.1 m/s to the north
b.
2.1 m/s to the south
d.
4.2 m/s to the south
 

96. 

A 2 kg mass moving to the right makes an elastic head-on collision with a 4 kg mass moving to the left at 4 m/s. The 2 kg mass reverses direction after the collision and moves at 3 m/s. The 4 kg mass moves to the left at 1 m/s. What was the initial velocity of the 2 kg mass?
a.
3 m/s to the right
c.
4 m/s to the left
b.
1 m/s to the left
d.
4 m/s to the right
 

97. 

Which of the following angles equals 2p rad?
a.
360°
c.
0°
b.
180°
d.
3.14°
 

98. 

One radian is equal to
a.
60°.
c.
57.3°.
b.
58°.
d.
56°.
 

99. 

How would an angle in radians be converted to an angle in degrees?
a.
The angle in radians would be multiplied by 180°/p.
b.
The angle in radians would be multiplied by 360°/p.
c.
The angle in radians would be multiplied by 180°/2p.
d.
The angle in radians would be multiplied by 2p/360°.
 

100. 

How would you convert an angle in degrees to an angle in radians?
a.
multiply the angle measured in degrees by 2p/180°
b.
multiply the angle measured in degrees by 2p/360°
c.
multiply the angle measured in degrees by p/360°
d.
multiply the angle measured in degrees by 2pr°
 

101. 

A cave dweller rotates a pebble in a sling with a radius of 0.30 m counterclockwise through an arc length of 0.96 m. What is the angular displacement of the pebble?
a.
1.6 rad
c.
3.2 rad
b.
–1.6 rad
d.
–3.2 rad
 

102. 

Earth has an equatorial radius of approximately 6380 km, and it rotates 360° every 24 h. What is the angular displacement of a person standing at the equator for 3.0 h?
a.
0.26 rad
c.
0.78 rad
b.
0.52 rad
d.
0.39 rad
 

103. 

A child sits on a carousel at a distance of 3.5 m from the center and rotates through an arc length of 6.5 m. What is the angular displacement of the child?
a.
1.9 rad
c.
3.0 rad
b.
0.93 rad
d.
5.0 rad
 

104. 

A bucket on the circumference of a water wheel travels an arc length of 18 m. If the radius of the wheel is 4.1 m, what is the angular displacement of the bucket?
a.
1.0 rad
c.
3.7 rad
b.
4.4 rad
d.
2.3 rad
 

105. 

What is the approximate angular speed of a wheel rotating at the rate of 5.0 rev/s?
a.
3.2 rad/s
c.
16 rad/s
b.
1.6 rad/s
d.
31 rad/s
 

106. 

A grinding wheel initially at rest with a radius of 0.15 m rotates until it reaches an angular speed of 12.0 rad/s in 4.0 s. What is the wheel's average angular acceleration?
a.
96 rad/s2
c.
3.0 rad/s2
b.
48 rad/s2
d.
0.33 rad/s2
 

107. 

A potter's wheel moves from rest to an angular speed of 0.54 rad/s in 30.0 s. What is the angular acceleration of the wheel?
a.
16 rad/s2
c.
0.018 rad/s2
b.
1.3 rad/s2
d.
0.042 rad/s2
 

108. 

A Ferris wheel initially at rest accelerates to a final angular speed of 0.70 rad/s and rotates through an angular displacement of 4.90 rad. What is the Ferris wheel's average angular acceleration?
a.
0.10 rad/s2
c.
1.80 rad/s2
b.
0.05 rad/s2
d.
0.60 rad/s2
 

109. 

A Ferris wheel rotates with an initial angular speed of 0.50 rad/s and accelerates over a 7.00 s interval at a rate of 4.0 ´ 10–2 rad/s2. What is its angular speed?
a.
0.20 rad/s
c.
0.46 rad/s
b.
0.30 rad/s
d.
0.78 rad/s
 

110. 

An automobile tire with a radius of 0.30 m starts at rest and accelerates at a constant angular acceleration of 2.0 rad/s2 for 5.0 s. What is the angular displacement of the tire?
a.
12 rad
c.
2.0 rad
b.
25 rad
d.
0.50 rad
 

111. 

A bicycle wheel rotates with a constant angular acceleration of 3.0 rad/s2. If the initial angular speed of the wheel is 1.5 rad/s, what is the angular displacement of the wheel after 4.0 s?
a.
6.0 rad
c.
3.0 ´ 101 rad
b.
24 rad
d.
36 rad
 

112. 

A gear in a machine accelerates at 11.2 rad/s2. If the wheel's initial angular speed is 5.40 rad/s, what is the wheel's angular speed after exactly 3.0 seconds?
a.
39.0 rad/s
c.
209 rad/s
b.
13.6 rad/s
d.
28.2 rad/s
 

113. 

A ball rolls downhill with an angular speed of 2.5 rad/s and has a constant angular acceleration of 2.0 rad/s2. If the ball takes 11.5 s to reach the bottom of the hill, what is the final angular speed of the ball?
a.
13 rad
c.
33 rad/s
b.
31 rad/s
d.
25.5 rad/s
 

114. 

A helicopter has 3.0 m long rotor blades that are rotating at an angular speed of 63 rad/s. What is the tangential speed of each blade tip?
a.
99 m/s
c.
21 m/s
b.
190 m/s
d.
66 m/s
 

115. 

A point on the rim of a 0.30 m radius rotating wheel has a tangential speed of 4.0 m/s. What is the tangential speed of a point 0.20 m from the center of the same wheel?
a.
0.8 m/s
c.
2.6 m/s
b.
1.3 m/s
d.
8.0 m/s
 

116. 

A cylinder with a diameter of 0.150 m rotates in a lathe at a constant angular speed of 35.6 rad/s. What is the tangential speed of the surface of the cylinder?
a.
2.67 m/s
c.
2.37 ´ 102 m/s
b.
5.34 m/s
d.
4.75 ´ 102 m/s
 

117. 

An automobile tire with a radius of 0.3 m accelerates from rest at a constant 2 rad/s2 over a 5 s interval. What is the tangential component of acceleration for a point on the outer edge of the tire?
a.
30 m/s2
c.
0.6 m/s2
b.
7 m/s2
d.
0.3 m/s2
 

118. 

A hamster gets on a stationary wheel with a radius of 0.15 m and runs until the wheel rotates at an angular speed of 12.0 rad/s in 4.0 s. What is the tangential acceleration of the wheel's edge?
a.
0.45 rad/s2
c.
0.65 rad/s2
b.
0.6 rad/s2
d.
1.30 rad/s2
 

119. 

A contestant in a game show spins a stationary wheel with a radius of 0.50 m so that it has a constant angular acceleration of 0.40 rad/s2. What is the tangential acceleration of a point on the edge of the wheel?
a.
0.20 m/s2
c.
1.3 m/s2
b.
0.60 m/s2
d.
0.73 m/s2
 

120. 

A stone on the edge of the tire of a unicycle wheel with a radius of 0.25 m has a centripetal acceleration of 4.0 m/s2. What is the tire's angular speed?
a.
1.0 rad/s
c.
3.2 rad/s
b.
2.0 rad/s
d.
4.0 rad/s
 

121. 

A point on the rim of a rotating wheel with a 0.37 m radius has a centripetal acceleration of 19.0 m/s2. What is the angular speed of the wheel?
a.
0.89 m/s
c.
3.2 rad/s
b.
1.6 rad/s
d.
7.2 rad/s
 

122. 

If the distance from the center of a merry-go-round to the edge is 1.2 m, what centripetal acceleration does a passenger experience when the merry-go-round rotates at an angular speed of 0.5 rad/s?
a.
1.7 m/s2
c.
0.3 m/s2
b.
0.9 m/s2
d.
0.6 m/s2
 

123. 

A 0.40 kg ball on a 0.50 m string rotates in a circular path in a vertical plane. If the angular speed of the ball at the bottom of the circle is 8.0 rad/s, what is the force that maintains circular motion?
a.
5.6 N
c.
13 N
b.
11 N
d.
20.0 N
 

124. 

A 0.40 kg ball on a 0.50 m string rotates in a circular path in a vertical plane. If a constant angular speed of 8.0 rad/s is maintained, what is the tension in the string when the ball is at the top of the circle?
a.
9.0 N
c.
13 N
b.
11 N
d.
10.0 N
 

125. 

A roller coaster loaded with passengers has a mass of 2.0 ´ 103 kg; the radius of curvature of the track at the lowest point of the track is 24 m. If the vehicle has a tangential speed of 18 m/s at this point, what force is exerted on the vehicle by the track?
a.
2.3 ´ 104 N
c.
3.0 ´ 104 N
b.
4.7 ´ 104 N
d.
2.7 ´ 104 N
 



 
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