Halliday/Resnick/Walker Fundamentals of Physics 8th edition

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Halliday/Resnick/WalkerFundamentals of Physics
8th edition

• Classroom Response System Questions

Chapter 8 Potential Energy and Conservation of
Energy
Reading Quiz Questions
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8.1.1. Which one of the following choices is not
a kind of potential energy? a) elastic b)
gravitational c) kinetic d) all of these are
potential energies
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8.1.1. Which one of the following choices is not
a kind of potential energy? a) elastic b)
gravitational c) kinetic d) all of these are
potential energies
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8.2.1. What is the relationship between the
gravitational potential energy of an object and
the work done on the object by the gravitational
force? a) The work is equal to the
gravitational potential energy. b) The negative
of the work is equal to the change in the
gravitational potential energy. c) The negative
of the work is equal to the square of the
gravitational potential energy. d) The work is
equal to the square of the gravitational
potential energy. e) The work is equal to
one-half of the gravitational potential energy.
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8.2.1. What is the relationship between the
gravitational potential energy of an object and
the work done on the object by the gravitational
force? a) The work is equal to the
gravitational potential energy. b) The negative
of the work is equal to the change in the
gravitational potential energy. c) The negative
of the work is equal to the square of the
gravitational potential energy. d) The work is
equal to the square of the gravitational
potential energy. e) The work is equal to
one-half of the gravitational potential energy.
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8.2.2. Complete the following statement A force
that acts on an object is said to be conservative
if a) the work it does on the object is equal
to the increase in the object's kinetic
energy b) the work it does on the object is
independent of the path of the motion. c) it
always acts in the direction of motion of the
object. d) it results in a change in the
object's kinetic energy. e) it obeys Newton's
laws of motion.
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8.2.2. Complete the following statement A force
that acts on an object is said to be conservative
if a) the work it does on the object is equal
to the increase in the object's kinetic
energy b) the work it does on the object is
independent of the path of the motion. c) it
always acts in the direction of motion of the
object. d) it results in a change in the
object's kinetic energy. e) it obeys Newton's
laws of motion.
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8.2.3. Which one of the following situations is
an example of a conservative force acting? a) A
boat motor produces a propulsion force that moves
the boat across a lake. b) The tension force in
the rope increased as the piano was lifted off
the ground. c) A child jumping on a trampoline
is pushed upward by an elastic spring force. d)
A normal force pushes upward on a book as it sits
on a table. e) The static frictional force
between the tires of a car and the road.
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8.2.3. Which one of the following situations is
an example of a conservative force acting? a) A
boat motor produces a propulsion force that moves
the boat across a lake. b) The tension force in
the rope increased as the piano was lifted off
the ground. c) A child jumping on a trampoline
is pushed upward by an elastic spring force. d)
A normal force pushes upward on a book as it sits
on a table. e) The static frictional force
between the tires of a car and the road.
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8.2.4. Which one of the following choices is an
example of a non-conservative force? a) elastic
spring force b) gravitational force c)
kinetic frictional force d) electrical
force e) tension
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8.2.4. Which one of the following choices is an
example of a non-conservative force? a) elastic
spring force b) gravitational force c)
kinetic frictional force d) electrical
force e) tension
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8.2.5. Complete the following statement In
situations involving non-conservative external
forces, the work done by these forces a) is
always negative. b) is always equal to
zero. c) is always positive. d) can be either
positive or negative. e) usually cannot be
determined.
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8.2.5. Complete the following statement In
situations involving non-conservative external
forces, the work done by these forces a) is
always negative. b) is always equal to
zero. c) is always positive. d) can be either
positive or negative. e) usually cannot be
determined.
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8.3.1. Complete the following statement The net
work done by a conservative force acting on an
object a) depends only on the time that the
force is exerted. b) depends only on the
velocity of the object. c) depends only on the
starting and ending points. d) is always equal
to zero joules. e) is always greater than zero
joules.
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8.3.1. Complete the following statement The net
work done by a conservative force acting on an
object a) depends only on the time that the
force is exerted. b) depends only on the
velocity of the object. c) depends only on the
starting and ending points. d) is always equal
to zero joules. e) is always greater than zero
joules.
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8.3.2. A ball is constrained to follow a circular
path by a conservative force. During a time
interval t, the ball makes exactly one
revolution. Which one of the following
statements concerning the net work done on the
ball during time t is true? a) The net work
depends only on the time t. b) The net work
depends only on the velocity of the ball. c)
The net work depends only on the radius of the
circle. d) The net work is equal to zero
joules. e) The net work is greater than zero
joules.
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8.3.2. A ball is constrained to follow a circular
path by a conservative force. During a time
interval t, the ball makes exactly one
revolution. Which one of the following
statements concerning the net work done on the
ball during time t is true? a) The net work
depends only on the time t. b) The net work
depends only on the velocity of the ball. c)
The net work depends only on the radius of the
circle. d) The net work is equal to zero
joules. e) The net work is greater than zero
joules.
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8.4.1. In which one of the following situations
is there a decrease in gravitational potential
energy? a) A large boulder rests at the bottom
of a steep hill. b) A helicopter takes off from
the roof of a hospital and flies due west. c) A
child accidentally releases a helium-filled
balloon and it flies upward into the clouds. d)
A girl jumps down from a bed and lands on her
feet. e) A truck drives at an average velocity
of 25 m/s, due north along a level, country road.
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8.4.1. In which one of the following situations
is there a decrease in gravitational potential
energy? a) A large boulder rests at the bottom
of a steep hill. b) A helicopter takes off from
the roof of a hospital and flies due west. c) A
child accidentally releases a helium-filled
balloon and it flies upward into the clouds. d)
A girl jumps down from a bed and lands on her
feet. e) A truck drives at an average velocity
of 25 m/s, due north along a level, country road.
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8.4.2. A man carries a 12-kg chair up one flight
of stairs to the second floor of his house. If
the second floor is 3.3 m above the first floor,
what is the change in the gravitational potential
energy of the chair? a) ?180 J b) 390 J c)
180 J d) ?390 J e) 240 J
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8.4.2. A man carries a 12-kg chair up one flight
of stairs to the second floor of his house. If
the second floor is 3.3 m above the first floor,
what is the change in the gravitational potential
energy of the chair? a) ?180 J b) 390 J c)
180 J d) ?390 J e) 240 J
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8.4.3. An object is initially at height y1.
After a time interval t, the object is located at
height y2. The work done by the gravitational
force on the object is dependent on which of the
following quantities? a) y1 ? y2 b) the path
taken from y1 to y2 c) the time interval t
taken to move from y1 to y2 d) choices a and
b e) choices a and c
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8.4.3. An object is initially at height y1.
After a time interval t, the object is located at
height y2. The work done by the gravitational
force on the object is dependent on which of the
following quantities? a) y1 ? y2 b) the path
taken from y1 to y2 c) the time interval t
taken to move from y1 to y2 d) choices a and
b e) choices a and c
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8.4.4. Which one of the following statements
concerning the elastic potential energy of a ball
attached to a vertical spring is false when the
ball is moving up and down in a periodic motion?
The position y 0 corresponds to the
unstretched, equilibrium position of the
spring. a) The elastic potential energy is at
its minimum when the spring is in its equilibrium
position. b) The elastic potential energy is
smaller when the ball is at ?y than when it is at
y. c) The elastic potential energy can be
expressed in units of watts. d) The elastic
potential energy is at its maximum when the
velocity of the ball is a maximum. e) The
elastic potential energy is at its minimum when
the acceleration of the ball is a maximum.
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8.4.4. Which one of the following statements
concerning the elastic potential energy of a ball
attached to a vertical spring is false when the
ball is moving up and down in a periodic motion?
The position y 0 corresponds to the
unstretched, equilibrium position of the
spring. a) The elastic potential energy is at
its minimum when the spring is in its equilibrium
position. b) The elastic potential energy is
smaller when the ball is at ?y than when it is at
y. c) The elastic potential energy can be
expressed in units of watts. d) The elastic
potential energy is at its maximum when the
velocity of the ball is a maximum. e) The
elastic potential energy is at its minimum when
the acceleration of the ball is a maximum.
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8.4.5. A ball is attached to a vertical spring.
The ball is initially supported at a height y so
that the spring is neither stretched nor
compressed. The ball is then released from rest
and it falls to a height y ? h before moving
upward. Consider the following quantities
translational kinetic energy, gravitational
potential energy, elastic potential energy. When
the ball was at a height y ? (h/2), which of the
listed quantities has (have) values other than
zero joules? a) translational kinetic energy
only b) gravitational potential energy only c)
elastic potential energy only d) translational
and elastic potential energies only e)
translational kinetic, gravitational potential,
and elastic potential energies
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8.4.5. A ball is attached to a vertical spring.
The ball is initially supported at a height y so
that the spring is neither stretched nor
compressed. The ball is then released from rest
and it falls to a height y ? h before moving
upward. Consider the following quantities
translational kinetic energy, gravitational
potential energy, elastic potential energy. When
the ball was at a height y ? (h/2), which of the
listed quantities has (have) values other than
zero joules? a) translational kinetic energy
only b) gravitational potential energy only c)
elastic potential energy only d) translational
and elastic potential energies only e)
translational kinetic, gravitational potential,
and elastic potential energies
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8.4.6. A block is attached to the end of a
spring. The block is then displaced from its
equilibrium position and released. Subsequently,
the block moves back and forth on a frictionless
surface without any losses due to friction.
Which one of the following statements concerning
the total mechanical energy of the block-spring
system this situation is true? a) The total
mechanical energy is dependent on the maximum
displacement during the motion. b) The total
mechanical energy is at its maximum when the
block is at its equilibrium position. c) The
total mechanical energy is constant as the block
moves back and forth. d) The total mechanical
energy is only dependent on the spring constant
and the mass of the block.
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8.4.6. A block is attached to the end of a
spring. The block is then displaced from its
equilibrium position and released. Subsequently,
the block moves back and forth on a frictionless
surface without any losses due to friction.
Which one of the following statements concerning
the total mechanical energy of the block-spring
system this situation is true? a) The total
mechanical energy is dependent on the maximum
displacement during the motion. b) The total
mechanical energy is at its maximum when the
block is at its equilibrium position. c) The
total mechanical energy is constant as the block
moves back and forth. d) The total mechanical
energy is only dependent on the spring constant
and the mass of the block.
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8.5.1. An arrow is launched straight up from the
surface of the Earth. Which one of the following
statements describes the energy transformation of
the arrow as it rises? Neglect air
resistance. a) The kinetic energy of the arrow
increases and its potential energy decreases. b)
Both the potential energy of the arrow and its
total energy increase. c) The kinetic energy of
the arrow decreases as the potential energy
increases. d) Both the kinetic energy of the
arrow and its potential energy remain
constant. e) The total energy of the arrow
increases.
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8.5.1. An arrow is launched straight up from the
surface of the Earth. Which one of the following
statements describes the energy transformation of
the arrow as it rises? Neglect air
resistance. a) The kinetic energy of the arrow
increases and its potential energy decreases. b)
Both the potential energy of the arrow and its
total energy increase. c) The kinetic energy of
the arrow decreases as the potential energy
increases. d) Both the kinetic energy of the
arrow and its potential energy remain
constant. e) The total energy of the arrow
increases.
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8.5.2. Which one of the following statements
concerning the principle of the conservation of
mechanical energy is true? a) Mechanical energy
is always conserved in situations where the
kinetic energy is constant. b) Mechanical
energy is always conserved in situations where
the gravitational potential energy is
constant. c) Mechanical energy is always
conserved in situations where external
non-conservative forces do no work. d)
Mechanical energy is always conserved in
situations where external conservative forces do
no work. e) Mechanical energy is always
conserved in situations where the gravitational
potential energy is zero joules.
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8.5.2. Which one of the following statements
concerning the principle of the conservation of
mechanical energy is true? a) Mechanical energy
is always conserved in situations where the
kinetic energy is constant. b) Mechanical
energy is always conserved in situations where
the gravitational potential energy is
constant. c) Mechanical energy is always
conserved in situations where external
non-conservative forces do no work. d)
Mechanical energy is always conserved in
situations where external conservative forces do
no work. e) Mechanical energy is always
conserved in situations where the gravitational
potential energy is zero joules.
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8.5.3. Complete the following statement In an
isolated system, the total mechanical energy
remains constant if a) all exerted forces are
conservative. b) all exerted forces are
nonconservative. c) the work done by
nonconservative forces is positive. d) the work
done by nonconservative forces is negative. e)
an object returns to its starting position.
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8.5.3. Complete the following statement In an
isolated system, the total mechanical energy
remains constant if a) all exerted forces are
conservative. b) all exerted forces are
nonconservative. c) the work done by
nonconservative forces is positive. d) the work
done by nonconservative forces is negative. e)
an object returns to its starting position.
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8.5.4. Complete the following statement The
total mechanical energy of a system remains
unchanged if a) the external forces acting on
the system are nonconservative. b) the external
forces acting on the system are conservative. c)
the kinetic energy is constant. d) the
potential energy is constant. e) there are no
external forces acting on the system.
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8.5.4. Complete the following statement The
total mechanical energy of a system remains
unchanged if a) the external forces acting on
the system are nonconservative. b) the external
forces acting on the system are conservative. c)
the kinetic energy is constant. d) the
potential energy is constant. e) there are no
external forces acting on the system.
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8.5.5. A ball is thrown vertically upward in the
air. Which one of the following quantities is
necessarily equal to zero at the highest point of
the balls trajectory? a) acceleration b) net
force c) potential energy d) kinetic
energy e) total mechanical energy
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8.5.5. A ball is thrown vertically upward in the
air. Which one of the following quantities is
necessarily equal to zero at the highest point of
the balls trajectory? a) acceleration b) net
force c) potential energy d) kinetic
energy e) total mechanical energy
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8.5.6. A pendulum is swinging back and forth with
no non-conservative forces acting on it. At the
highest points of its trajectory, the kinetic
energy of the pendulum bob is instantaneously
equal to zero joules. At the lowest point of its
trajectory, the potential energy is
instantaneously equal to zero joules. Which one
of the following expressions describes the
kinetic and potential energies at the point
mid-way between to the highest and lowest
points? a) K 0, U Umax b) K U c) K gt
U d) K lt U e) U 0, K Kmax
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8.5.6. A pendulum is swinging back and forth with
no non-conservative forces acting on it. At the
highest points of its trajectory, the kinetic
energy of the pendulum bob is instantaneously
equal to zero joules. At the lowest point of its
trajectory, the potential energy is
instantaneously equal to zero joules. Which one
of the following expressions describes the
kinetic and potential energies at the point
mid-way between to the highest and lowest
points? a) K 0, U Umax b) K U c) K gt
U d) K lt U e) U 0, K Kmax
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8.6.1. Which one of the following situations is
an example of neutral equilibrium? a) a marble
is sitting on a flat tabletop b) a pendulum is
swinging c) a ball is rolling down a hill d)
a block is bobbing up and down on a vertical
spring e) a horse is jumping over a fence with
all four hooves above the ground
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8.6.1. Which one of the following situations is
an example of neutral equilibrium? a) a marble
is sitting on a flat tabletop b) a pendulum is
swinging c) a ball is rolling down a hill d)
a block is bobbing up and down on a vertical
spring e) a horse is jumping over a fence with
all four hooves above the ground
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8.6.2. Which one of the following phrases
describes what occurs at a turning point? a)
The net force acting an object is zero
newtons. b) The kinetic energy of the object is
equal to zero joules. c) The object is at an
unstable equilibrium point. d) The potential
energy of the object is equal to zero joules. e)
The potential energy of the object is at its
maximum value.
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8.6.2. Which one of the following phrases
describes what occurs at a turning point? a)
The net force acting an object is zero
newtons. b) The kinetic energy of the object is
equal to zero joules. c) The object is at an
unstable equilibrium point. d) The potential
energy of the object is equal to zero joules. e)
The potential energy of the object is at its
maximum value.
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8.6.3. Which one of the following statements
correctly describes a stationary object at an
unstable equilibrium point? a) The object
experiences a net force equal to zero
newtons. b) The object will start to move after
some period of time. c) The object will move
directly to a stationary equilibrium point if it
is displaced. d) The object will oscillate
about an equilibrium point if it is
displaced. e) The object will move to a
position with higher potential energy if it is
displaced.
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8.6.3. Which one of the following statements
correctly describes a stationary object at an
unstable equilibrium point? a) The object
experiences a net force equal to zero
newtons. b) The object will start to move after
some period of time. c) The object will move
directly to a stationary equilibrium point if it
is displaced. d) The object will oscillate
about an equilibrium point if it is
displaced. e) The object will move to a
position with higher potential energy if it is
displaced.
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8.6.4. The graph shows the potential energy as a
function of distance for an object moving along
the x axis. At which of the labeled points does
the force acting on the object have the largest
magnitude? a) A b) B c) C d) D e) E
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8.6.4. The graph shows the potential energy as a
function of distance for an object moving along
the x axis. At which of the labeled points does
the force acting on the object have the largest
magnitude? a) A b) B c) C d) D e) E
50
8.6.5. The graph shows the potential energy as a
function of distance for an object moving along
the x axis. At which of the labeled points does
the force acting on the object have the least
magnitude? a) A b) B c) C d) D e) The
force is the same at each of the four points.
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8.6.5. The graph shows the potential energy as a
function of distance for an object moving along
the x axis. At which of the labeled points does
the force acting on the object have the least
magnitude? a) A b) B c) C d) D e) The
force is the same at each of the four points.
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8.6.6. The graph shows the potential energy as a
function of distance for an object moving along
the x axis. At which of the labeled points does
the object have greatest speed? a) A b) B c)
C d) D e) E
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8.6.6. The graph shows the potential energy as a
function of distance for an object moving along
the x axis. At which of the labeled points does
the object have greatest speed? a) A b) B c)
C d) D e) E
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8.8.1. Which one of the following statements
concerning the principle of conservation of
energy is false? a) The total energy in the
universe has a constant value. b) Kinetic
energy may be converted into gravitational
potential energy and heat. c) Thermal energy
may be converted into kinetic energy and kinetic
energy may be converted into thermal energy. d)
Chemical energy may be converted into thermal
energy and gravitational potential energy. e)
The net work done on an object must be zero
joules since energy is neither created nor
destroyed in the process.
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8.8.1. Which one of the following statements
concerning the principle of conservation of
energy is false? a) The total energy in the
universe has a constant value. b) Kinetic
energy may be converted into gravitational
potential energy and heat. c) Thermal energy
may be converted into kinetic energy and kinetic
energy may be converted into thermal energy. d)
Chemical energy may be converted into thermal
energy and gravitational potential energy. e)
The net work done on an object must be zero
joules since energy is neither created nor
destroyed in the process.
56
8.8.2. Complete the following statement The
total energy of a system can only change a) if
the forces acting in the system are
nonconservative. b) if there are no external
forces acting on the system. c) if the forces
acting in the system are conservative. d) by
transferring amounts of energy to or from the
system. e) if there is more than one force
acting on the system.
57
8.8.2. Complete the following statement The
total energy of a system can only change a) if
the forces acting in the system are
nonconservative. b) if there are no external
forces acting on the system. c) if the forces
acting in the system are conservative. d) by
transferring amounts of energy to or from the
system. e) if there is more than one force
acting on the system.