True/False
Indicate using an upper case 'T' or
'F' whether the sentence or statement is true or false.
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| 1. | If a
person tries to lift a heavy box for 5 seconds and can't make it budge, the work done on the box is
equal to the amount of energy the person uses.
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| 2. | Machines decrease the amount of energy that is needed to do work.
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| 3. | Because of friction, using machines increases the amount of energy that is needed to
do work.
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| 4. | A
pulley system always causes the direction of the output force to be opposite to the direction of the
input force.
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| 5. | A
first-class lever can have an input force greater than the output force.
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| 6. | A
second-class lever always has an input force that is less than the output force.
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| 7. | Increasing the angle a ramp makes with the horizontal decreases the mechanical
advantage.
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| 8. | The
flow of charged particles through a conductor is a form of energy called electricity.
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| 9. | A
meteorologist trying to predict global warming would consider Earth to be a closed
system.
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| 10. | A
ball falling under the force of gravity is a closed system.
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| 11. | Increasing the length of a ramp increases the efficiency of the ramp.
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Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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| 12. | 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 | c. | zero | b. | 200 J | d. | can't be determined | | | | |
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| 13. | What
are the units of work? a. | J | c. | kg•m2/s2 | b. | N•m | d. | all of the
above | | | | |
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| 14. | 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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| 15. | 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 | c. | zero | b. | 220 N | d. | 145 J | | | | |
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| 16. | What
are the units of power? a. | watts | c. | joules per second | b. | horsepower | d. | all of the
above | | | | |
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| 17. | 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 | c. | 400
watts | b. | 25 watts | d. | 100 watts | | | | |
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| 18. | What
is the mechanical advantage of a ramp that is 10 meters long and 2 meters high?
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| 19. | 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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| 20. | 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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| 21. | A
wheelbarrow is an example of a a. | first-class lever. | c. | third-class lever. | b. | second-class
lever. | d. | fourth-class
lever. | | | | |
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| 22. | Which
of the following is an example of a third-class lever? a. | a
nutcracker | c. | a crow
bar | b. | a hand-held boat
paddle | d. | a
screw | | | | |
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| 23. | Which
of the following is not a simple machine? a. | a lever | c. | a screw | b. | a pair of
scissors | d. | a wheel and
axle | | | | |
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| 24. | What
is the mechanical advantage of a single fixed pulley?
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| 25. | What
is the mechanical advantage of a single movable pulley?
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| 26. | Which
of the following is an example of a wheel and axle? a. | a block and
tackle | c. | a
screwdriver | b. | a pulley | d. | a nutcracker | | | | |
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| 27. | 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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| 28. | Which
of the following is not in the inclined plane family? a. | a
wedge | c. | a
ramp | b. | a
screw | d. | a wheel and
axle | | | | |
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| 29. | Which
of the following is a compound machine? a. | a wheel and axle | c. | a pair of pliers | b. | a
pulley | d. | a
ramp | | | | |
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| 30. | 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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| 31. | What
is the gravitational potential energy of a 55 kg box that is 8.0 m above the ground? a. | 5500
J | c. | 4300
J | b. | 3400
J | d. | 550
J | | | | |
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| 32. | Gravitational potential energy depends on the ____ a. | the mass of the
object. | c. | the acceleration
due to gravity. | b. | the height of the object. | d. | All of the above | | | | |
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| 33. | 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 | c. | 2000
J | b. | 10
J | d. | 500
J | | | | |
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| 34. | Which
of the following is an example of mechanical energy? a. | nuclear
energy | c. | potential
energy | b. | chemical energy | d. | light energy | | | | |
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| 35. | The
kind of energy associated with atomic bonds is a. | nuclear energy. | c. | chemical energy. | b. | light
energy. | d. | kinetic
energy. | | | | |
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| 36. | The
primary source of the sun's energy is a. | chemical energy. | c. | nuclear fission. | b. | nuclear
fusion. | d. | potential
energy. | | | | |
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| 37. | 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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| 38. | 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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| 39. | 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 | c. | 240
J | b. | 310
J | d. | 180
J | | | | |
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| 40. | 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?
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| 41. | 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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| 42. | 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 | c. | 2100
J | b. | 75
J | d. | 4625
J | | | | |
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| 43. | 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 | c. | 8
m/s | b. | 9
m/s | d. | 7
m/s | | | | |
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| 44. | 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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Completion
Complete each sentence or
statement.
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| | 45. | ____________________ is a quantity that measures the effects of a force acting over a
distance.
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| | 46. | ____________________ is a quantity that measures the rate at which work is
done.
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| | 47. | ____________________ is a quantity that measures how much a machine multiplies force
or distance.
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| | 48. | Power
is calculated by dividing work by ____________________ .
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| | 49. | Horsepower is the common unit of power in rating engines. However, the official SI
unit of power is the ____________________.
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| | 50. | All
levers have a rigid arm that turns around a point called the ____________________.
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| | 51. | A
____________________ is defined as a machine made up of more than one simple machine.
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| | 52. | A(n)
____________________ is an inclined plane wrapped around a cylinder.
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| | 53. | ____________________ can be defined as the ability to do work.
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| | 54. | The
formula for calculating kinetic energy can be written as ____________________.
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| | 55. | ____________________ is the stored energy resulting from the relative positions of
objects in a system.
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| | 56. | ____________________is the energy of a moving object due to its motion.
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| | 57. | The
sum of the kinetic and potential energy of large-scale objects in a system is called
____________________.
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| | 58. | Energy that lies at the level of atoms and does not affect motion on a large scale is
sometimes called ____________________ energy.
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| | 59. | The
source of the energy when dynamite explodes is ____________________ energy.
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| | 60. | The
process that transforms light energy into chemical energy in plants is called
____________________.
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| | 61. | The
source of the sun's energy is ____________________.
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| | 62. | When
a system exchanges energy with the environment outside the system, it is called a(n)
____________________.
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| | 63. | A(n)
____________________ exchanges energy with the outside.
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| | 64. | ____________________ measures the ratio of useful work output to work
input.
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| | 65. | Energy is transferred as ____________________ when mechanical energy decreases and
temperature increases.
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Matching
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Match
the following: a. | | e. | Pulley | b. | J | f. | stored
energy | c. | W | g. | energy of motion | d. | Mechanical
Advantage | h. | efficiency | | | | |
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| 66. | Energy
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| 67. | Same
as joules
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| 68. | Force
in vs Force out
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| 69. | Potential energy
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| 70. | simple machine
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| 71. | Kinetic energy
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| 72. | Power
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| 73. | Work
in vs work out
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