Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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A boy
pushes on a parked car with a force of 200 N. The car does not move. How much work does the boy do on
the car?
a. 200 N b. 200 J
c. zero d. can't be determined
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2.
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What
are the units of work?
a. J b. N•m
c. kg•m2/s2 d. all of the above
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3.
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Which
of the following processes requires the most work?
a. A 10 kg
weight rests on a table. b. A person holds a 1 kg weight still with outstretched
arms. c. A person lifts a 1 kg weight 1 m off the floor. d. A 10 kg
ball is rolled across the floor at a constant speed for a distance of 10 m.
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4.
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A man
pushes a crate along a factory floor by exerting a force of 55 N. If the crate moves a distance of
4.0 m, how much work does the man perform?
a. 165
N b. 220 N c. zero d. 145 J
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5.
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What
are the units of power?
a. watts b. horsepower
c. joules per second d. all of the above
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6.
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A
weight lifter presses a 400 N weight 0.5 m over his head in 2 seconds. What is the power of the
weight lifter?
a. 100 N b. 25 watts c. 400
watts d. 100 watts
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7.
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What
is the mechanical advantage of a ramp that is 10 meters long and 2 meters
high?
a. 20 b. 5 c. 8
d. 15
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8.
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A
machine is a device that
a. requires less work to do a given task.
b. decreases the amount of work done by a given force. c. increases
energy. d. can multiply and change the direction of an input force.
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9.
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A
first-class lever has the
a. fulcrum at one end and the output force between the
fulcrum and the input force. b. fulcrum at one end and the input force between the
fulcrum and the output force. c. fulcrum in the middle. d. input
force in the middle.
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10.
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A
wheelbarrow is an example of a
a. first-class lever.
b. second-class lever. c. third-class lever. d. fourth-class
lever.
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11.
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Which
of the following is an example of a third-class lever?
a. a
nutcracker b. a hand-held boat paddle c. a crow bar
d. a screw
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12.
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Which
of the following is not a simple machine?
a. a
lever b. a pair of scissors c. a screw d. a wheel
and axle
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13.
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What
is the mechanical advantage of a single fixed pulley?
a. 1 b. 1.5 c. 2
d. 3
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14.
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What
is the mechanical advantage of a single movable pulley?
a. 1 b. 1.5 c. 2
d. 3
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15.
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Which
of the following is an example of a wheel and axle?
a. a block
and tackle b. a pulley c. a screwdriver d. a
nutcracker
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16.
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An
inclined plane
a. changes the direction of the force only.
b. changes the magnitude of the force only. c. changes both the magnitude and
the direction of the force. d. decreases the amount of work done.
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17.
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Which
of the following is not in the inclined plane family?
a. a
wedge b. a screw c. a ramp d. a wheel and
axle
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18.
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Which
of the following is a compound machine?
a. a wheel
and axle b. a pulley c. a pair of pliers d. a
ramp
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19.
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Which
of the following statements about work and energy is not true?
a. When
work is done, energy is transferred or transformed. b. Energy may be defined as the
ability to do work. c. Work and energy are always equal. d. Work
and energy have the same units.
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20.
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What
is the gravitational potential energy of a 55 kg box that is 8.0 m above the
ground?
a. 5500 J b. 3400 J c. 4300
J d. 550 J
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21.
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Gravitational potential energy depends on the ____
a. the mass
of the object. b. the height of the object. c. the acceleration due
to gravity. d. All of the above
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22.
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A
medicine ball has a mass of 5 kg and is thrown with a speed of 2 m/s. What is its kinetic
energy?
a. 100 J b. 10 J c. 2000
J d. 500 J
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23.
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Which
of the following is an example of mechanical energy?
a. nuclear
energy b. chemical energy c. potential energy
d. light energy
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24.
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The
kind of energy associated with atomic bonds is
a. nuclear
energy. b. light energy. c. chemical energy.
d. kinetic energy.
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25.
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The
primary source of the sun's energy is
a. chemical
energy. b. nuclear fusion. c. nuclear fission.
d. potential energy.
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26.
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A
pendulum is swinging back and forth and has a kinetic energy of 400 J at a particular point in its
path. Which of the following statements is not true?
a. Both the
kinetic and potential energy are decreasing. b. The minimum kinetic energy is
zero. c. When the kinetic energy is zero, the potential energy will be 400 J
greater. d. The potential energy increases when the kinetic energy
decreases.
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27.
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Which
of the following statements is not true?
a. The
energy of a closed system is constant. b. The energy of an open system can
increase. c. If the kinetic energy of an object decreases, the nonmechanical energy
will decrease. d. Energy cannot be created or destroyed.
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28.
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The
efficiency of a ramp is 75%. If the amount of work input is 240 J, what is the amount of useful work
output?
a. 320 J b. 310 J c. 240
J d. 180 J
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29.
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The
brakes on a car exert a frictional force of 6000 N in getting the car to stop. If the work done by
the brakes is 120 000 J in coming to a stop, how many meters did the car travel after the driver
applied the brakes?
a. 6 m b. 20 m c. 12
m d. 40 m
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30.
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A
pair of tweezers is
a. a first-class lever. b. a compound machine
made of two third-class levers. c. a compound machine made of two second-class
levers. d. a kind of wedge.
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31.
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An
object weighing 75 N is dropped from the top of a building and falls a distance of 28 m to the
ground. How much work does gravity do on the object from the time it is dropped to the time it hits
the ground?
a. zero b. 75 J c. 2100
J d. 4625 J
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32.
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An
object has a kinetic energy of 810 J after falling a certain distance. If the mass of the object is
20 kg, what is the speed of the object at this time?
a. cannot
be determined b. 9 m/s c. 8 m/s d. 7
m/s
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33.
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The
law of conservation of energy states that
a. the
energy of a system can disappear. b. it is impossible to make a perpetual motion
machine. c. energy cannot change form. d. energy can neither be
created nor destroyed.
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