Halliday/Resnick/Walker
Fundamentals of Physics 8th edition
Classroom Response System Questions
Chapter 8 Potential Energy and Conservation of
Energy
Reading Quiz Questions
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
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
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.
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.
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.
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.
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.
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.
8.2.4. Which one of the following choices is an example of a nonconservative force?
a) elastic spring force
b) gravitational force
c) kinetic frictional force
d) electrical force
e) tension
8.2.4. Which one of the following choices is an example of a nonconservative force?
a) elastic spring force
b) gravitational force
c) kinetic frictional force
d) electrical force
e) tension
8.2.5. Complete the following statement: In situations involving nonconservative 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.
8.2.5. Complete the following statement: In situations involving nonconservative 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.
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.
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.
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.
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.
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.
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.
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
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
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
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
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.
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.
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
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
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 blockspring 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.
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 blockspring 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.
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.
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.
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 nonconservative 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.
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 nonconservative 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.
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.
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.
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.
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.
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 ball’s trajectory?
a) acceleration
b) net force
c) potential energy
d) kinetic energy
e) total mechanical energy
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 ball’s trajectory?
a) acceleration
b) net force
c) potential energy
d) kinetic energy
e) total mechanical energy
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 > U
d) K < U
e) U = 0, K = Kmax
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 > U
d) K < U
e) U = 0, K = Kmax
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
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
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.
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.
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.
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.
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
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
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.
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.
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
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
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.
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.
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.
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.