Download 1. In which one of the following situations is zero

Name: __________________________ Date: _____________
1. In which one of the following situations is zero net work done?
A) A ball rolls down an inclined plane.
B) A physics student stretches a spring.
C) A projectile falls toward the surface of Earth.
D) A box is pulled across a rough floor at constant velocity.
E) A child pulls a wagon across a rough surface causing it to accelerate.
2. Work may be expressed using all of the following units except:
A) N  m
B) joule
C) erg
D) ft  lb
E) watt
3. Mike is cutting the grass using a human-powered lawn mower. He pushes the mower
with a force of 45 N directed at an angle of 41° below the horizontal direction.
Calculate the work that Mike does on the mower in pushing it 9.1 m across the yard.
A) 510 J
B) 460 J
C) 410 J
D) 360 J
E) 310 J
4. A 1.0-kg ball on the end of a string is whirled at a constant speed of 2.0 m/s in a
horizontal circle of radius 1.5 m. What is the work done by the centripetal force during
one revolution?
A) zero joules
B) 2.7 J
C) 6.0 J
D) 25 J
E) 33 J
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5. Which one of the following situations is an example of an object with a non-zero kinetic
energy?
A) a drum of diesel fuel on a parked truck
B) a stationary pendulum
C) a satellite in geosynchronous orbit
D) a car parked at the top of a hill
E) a boulder resting at the bottom of a cliff
6. Which one of the following statements concerning kinetic energy is true?
A) Kinetic energy can be measured in watts.
B) Kinetic energy is always equal to the potential energy.
C) Kinetic energy is always positive.
D) Kinetic energy is a quantitative measure of inertia.
E) Kinetic energy is directly proportional to velocity.
7. Which one of the following has the largest kinetic energy?
A) a raindrop falling
B) a woman swimming
C) a jet airplane flying at its maximum speed
D) the earth moving in its orbit around the sun
E) the space shuttle orbiting the Earth
8. In which one of the following situations will there be an increase in kinetic energy?
A) A projectile approaches its maximum height.
B) A child pushes a merry go round causing it to rotate faster.
C) A box is pulled across a rough floor at constant speed.
D) A satellite travels in a circular orbit around the earth at fixed altitude.
E) A stone at the end of a string is whirled in a horizontal circle at constant speed.
9. How much energy is dissipated in braking a 1000-kg car to a stop from an initial speed
of 20 m/s?
A) 20 000 J
B) 200 000 J
C) 400 000 J
D) 800 000 J
E) 10 000 J
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10. A 10.0-g bullet traveling horizontally at 755 m/s strikes a stationary target and stops
after penetrating 14.5 cm into the target. What is the average force of the target on the
bullet?
A) 1.97 × 104 N
B) 2.07 × 105 N
C) 6.26 × 103 N
D) 3.13 × 104 N
E) 3.93 × 104 N
11. A car is traveling at 7.0 m/s when the driver applies the brakes. The car moves 1.5 m
before it comes to a complete stop. If the car had been moving at 14 m/s, how far
would it have continued to move after the brakes were applied? Assume the braking
force is constant.
A) 1.5 m
B) 3.0 m
C) 4.5 m
D) 6.0 m
E) 7.5 m
12. In which one of the following systems is there a decrease in gravitational potential
energy?
A) a boy stretches a horizontal spring
B) a girl jumps down from a bed
C) a crate rests at the bottom of an inclined plane
D) a car ascends a steep hill
E) water is forced upward through a pipe
13. An elevator supported by a single cable descends a shaft at a constant speed. The only
forces acting on the elevator are the tension in the cable and the gravitational force.
Which one of the following statements is true?
A) The magnitude of the work done by the tension force is larger than that done by the
gravitational force.
B) The magnitude of the work done by the gravitational force is larger than that done
by the tension force.
C) The work done by the tension force is zero joules.
D) The work done by the gravitational force is zero joules.
E) The net work done by the two forces is zero joules.
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14. Two balls of equal size are dropped from the same height from the roof of a building.
One ball has twice the mass of the other. When the balls reach the ground, how do the
kinetic energies of the two balls compare?
A) The lighter one has one fourth as much kinetic energy as the other does.
B) The lighter one has one half as much kinetic energy as the other does.
C) The lighter one has the same kinetic energy as the other does.
D) The lighter one has twice as much kinetic energy as the other does.
E) The lighter one has four times as much kinetic energy as the other does.
15. A woman stands on the edge of a cliff and throws a stone vertically downward with an
initial speed of 10 m/s. The instant before the stone hits the ground below, it has 450 J
of kinetic energy. If she were to throw the stone horizontally outward from the cliff
with the same initial speed of 10 m/s, how much kinetic energy would it have just
before it hits the ground?
A) 50 J
B) 100 J
C) 450 J
D) 800 J
E) 950 J
16. A donkey pulls a crate up a rough, inclined plane at constant speed. Which one of the
following statements concerning this situation is false?
A) The gravitational potential energy of the crate is increasing.
B) The net work done by all the forces acting on the crate is zero joules.
C) The work done on the crate by the normal force of the plane is zero joules.
D) The donkey does "positive" work in pulling the crate up the incline.
E) The work done on the object by gravity is zero joules.
17. A block is dropped from a high tower and is falling freely under the influence of
gravity. Which one of the following statements is true concerning this situation?
Neglect air resistance.
A) As the block falls, the net work done by all of the forces acting on the block is zero
joules.
B) The kinetic energy increases by equal amounts over equal distances.
C) The kinetic energy of the block increases by equal amounts in equal times.
D) The potential energy of the block decreases by equal amounts in equal times.
E) The total energy of the block increases by equal amounts over equal distances.
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18. A rock is thrown straight up from the surface of the Earth. Which one of the following
statements describes the energy transformation of the rock as it rises? Neglect air
resistance.
A) The total energy of the rock increases.
B) The kinetic energy increases and the potential energy decreases.
C) Both the potential energy and the total energy of the rock increase.
D) The kinetic energy decreases and the potential energy increases.
E) Both the kinetic energy and the potential energy of the rock remain the same.
19. A roller-coaster car is moving at 20 m/s along a straight horizontal track. What will its
speed be after climbing the 15-m hill shown in the figure, if friction is ignored?
A)
B)
C)
D)
E)
17 m/s
7 m/s
5 m/s
10 m/s
14 m/s
20. A roller coaster starts from rest at the top of an 18-m hill as shown. The car travels to
the bottom of the hill and continues up the next hill that is 10.0 m high.
How fast is the car moving at the top of the 10.0-m hill, if friction is ignored?
A) 6.4 m/s
B) 8.1 m/s
C) 13 m/s
D) 18 m/s
E) 27 m/s
21. What power is needed to lift a 49-kg person a vertical distance of 5.0 m in 20.0 s?
A) 12.5 W
B) 25 W
C) 60 W
D) 120 W
E) 210 W
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Answer Key
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D
E
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A
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B
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B
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D
C
D
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