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1. A 20.-kilogram object strikes the ground with 1960 joules of
kinetic energy after falling freely from rest. How far above the
ground was the object when it was released?
A. 10. m
B. 14 m
C. 98 m
D. 200 m
7. A motor has an output of 1,000 watts. When the motor is
working at full capacity, how much time will it require to lift a 50newton weight 100 meters?
A. 5 s
B. 10 s
C. 50 s
D. 100 s
2. As the time required to do a given quantity of work
decreases, the power developed
A. decreases
B. increases
C. remains the same
8. When a 5-kilogram mass is lifted from the ground to a height
of 10 meters, the gravitational potential energy of the mass is
increased by approximately
A. 0.5 J
B. 2 J
C. 50 J
D. 500 J
3. As the speed of a bicycle moving along a horizontal surface
increases from 2 meters per second to 4 meters per second, the
magnitude of the bicycle's gravitational potential energy
A. decreases
B. increases
C. remains the same
4. A jack exerts a force of 4,500 newtons to raise a car 0.25
meter. What is the approximate work done by the jack?
A. 5.6 × 10-5 J
B. 1.1 × 103 J
C. 4.5 × 103 J
9. Work is being done when a force
A. acts vertically on a cart that can only move horizontally
B. is exerted by one team in a tug of war when there is no
movement
C. is exerted on a wagon while pulling it up a hill
D. of gravitational attraction acts on a person standing on
the surface of the Earth
10. As the pendulum swings from position A to position C as
shown in the diagram below, what is the relationship of kinetic
energy to potential energy? [Neglect friction.]
D. 1.8 × 104 J
5. Three people of equal mass climb a mountain using paths A,
B, and C shown in the diagram.
Along which path(s) does a person gain the greatest amount of
gravitational potential energy?
A. B. C. D. A, only
B, only
C, only
The gain is the same along all paths.
6. As an object falls freely near the Earth's surface, the loss in
gravitational potential energy of the object is equal to its
A. loss of height
B. loss of mass
C. gain in velocity
D. gain in kinetic energy
A. The kinetic energy decreases more than the potential
energy increases.
B. The kinetic energy increases more than the potential
energy decreases.
C. The kinetic energy decrease is equal to the potential
energy increase.
D. The kinetic energy increase is equal to the potential
energy decrease.
11. The diagram shows a 1.0 × 103 -newton crate to be lifted at
constant speed from the ground to a loading dock 1.5 meters
high in 5.0 seconds.
What power is required to lift the crate?
A. 1.5 × 103 W
B. 2.0 × 102 W
14. Which action would require no work to be done on an
object?
A. lifting the object from the floor to the ceiling
B. pushing the object along a horizontal floor against a
frictional force
C. decreasing the speed of an object until it comes to rest
D. holding the object stationary above the ground
15. A 60.-kilogram student running at 3.0 meters per second
has a kinetic energy of
A. 180 J
B. 270 J
C. 540 J
D. 8100 J
12. An object with a speed of 20. meters per second has a
kinetic energy of 400. joules. The mass of the object is
A. 1.0 kg
B. 2.0 kg
C. 0.50 kg
D. 40. kg
16. A girl rides an escalator that moves her upward at a
constant speed. As the girl rises, how do her gravitational
energy and kinetic energy change?
A. Gravitational potential energy decreases and kinetic
energy decreases.
B. Gravitational potential energy decreases and kinetic
energy remains the same.
C. Gravitational potential energy increases and kinetic
energy decreases.
D. Gravitational potential energy increases and kinetic
energy remains the same.
13. In the diagram, an ideal pendulum released from point A
swings freely through point B .
17. In the diagram below, an average force of 20. newtons is
used to pull back the string of a bow 0.60 meter.
C. 3.0 × 102 W
D. 7.5 × 103 W
As the arrow leaves the bow, its kinetic energy is
Compared to the pendulum's kinetic energy at A, its potential
energy at B is
A. B. C. D. half as great
twice as great
the same
four times as great
A. B. C. D. 3.4 J
6.0 J
12 J
33 J
18. A 5.0 × 102 -newton girl takes 10. seconds to run up two
flights of stairs to a landing, a total of 5.0 meters vertically above
her starting point. What power does the girl develop during her
run?
A. 25 W
B. 50. W
C. 250 W
D. 2,500 W
23. A 3.0-kilogram block is initially at rest on a frictionless,
horizontal surface. The block is moved 8.0 meters in 2.0
seconds by the application of a 12-newton horizontal force, as
shown in the diagram below.
What is the average power developed while moving the block?
19. An object moving at a constant speed of 25 meters per
second possesses 450 joules of kinetic energy. What is the
object’s mass?
A. 0.72 kg
B. 1.4 kg
C. 18 kg
D. 36 kg
20. Which graph best represents the relationship between the
gravitational potential energy of a freely falling object and the
object’s height above the ground near the surface of Earth?
C. A. B. D. 21. An object weighing 15 newtons is lifted from the ground to a
height of 0.22 meter. The increase in the object’s gravitational
potential energy is approximately
A. 310 J
B. 32 J
C. 3.3 J
D. 0.34 J
22. As an object falls freely, the kinetic energy of the object
A. decreases
B. increases
C. remains the same
A. B. C. D. 24 W
32 W
48 W
96 W
24. What is the average power developed by a motor as it lifts
a 400.-kilogram mass at constant speed through a vertical
distance of 10.0 meters in 8.0 seconds?
A. 320 W
B. 500 W
C. 4,900 W
D. 32,000 W
25. The work done in moving a block across a rough surface
and the heat energy gained by the block can both be measured
in
A. watts
B. degrees
C. newtons
D. joules
26. Base your answer to the question on the information below.
A 75-kilogram athlete jogs 1.8 kilometers along a straight road
in 1.2 × 103 seconds.
Determine the average speed of the athlete in meters per
second.
Answer: m/s
Calculate the average kinetic energy of the athlete.
Answer: KE = J
Figure 1
Base your answer to the question on the information below.
A roller coaster car has a mass of 290. kilograms. Starting from rest, the car acquires 3.13 × 105 joules of kinetic energy as it descends to the
bottom of a hill in 5.3 seconds.
27. [Refer to figure 1]
Calculate the speed of the roller coaster car at the bottom of the
hill.
Answer: m/s
28. [Refer to figure 1]
Calculate the magnitude of the average acceleration of the roller
coaster car as it descends to the bottom of the hill.
Answer: m/s2
Answer Key for Energy Practice APS
1. A 11. C 21. C
2. B 12. B 22. B
3. C 13. C 23. C
4. B 14. D 24. C
5. D 15. B 25. D
6. D 16. D 26. 1.5, 84
7. A 17. C 27. 46.5
8. D 18. C 28. 8.8
9. C 19. B 10. D 20. A