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Halliday/Resnick/Walker

Fundamentals 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 onerevolution. Which one of the following statements concerning the

net work done on the ball during time tis 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 onerevolution. Which one of the following statements concerning the

net work done on the ball during time tis 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 firstfloor, 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 firstfloor, 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 heighty1. After a time interval t, the

object is located at heighty2. The work done by the gravitationalforce on the object is dependent on which of the following

quantities?

a) y1y2

b) the path taken fromy1 toy2

c) the time interval ttaken to move fromy1 toy2

d) choices a and b

e) choices a and c

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8.4.3. An object is initially at heighty1. After a time interval t, the

object is located at heighty2. The work done by the gravitationalforce on the object is dependent on which of the following

quantities?

a) y1y2

b) the path taken fromy1 toy2

c) the time interval ttaken to move fromy1 toy2

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 positiony= 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 ythan 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 amaximum.

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 positiony= 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 ythan 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 amaximum.

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

yso that the spring is neither stretched nor compressed. The ball is then

released from rest and it falls to a heightyhbefore moving upward. Consider

the following quantities: translational kinetic energy, gravitational potential

energy, elastic potential energy. When the ball was at a heighty (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

yso that the spring is neither stretched nor compressed. The ball is then

released from rest and it falls to a heightyhbefore moving upward. Consider

the following quantities: translational kinetic energy, gravitational potential

energy, elastic potential energy. When the ball was at a heighty (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 ofthe 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 ofthe 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 conservativeforces 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 conservativeforces 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 highestpoint 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 highestpoint 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> U

d) K< 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> U

d) K< 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 isdisplaced.

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 isdisplaced.

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 functionof distance for an object

moving along the xaxis. 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 functionof distance for an object

moving along the xaxis. 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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8.6.5. 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 functionof distance for an object

moving along the xaxis. 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 functionof distance for an object

moving along the xaxis. 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 gravitationalpotential 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 gravitationalpotential 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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8.8.2. 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.

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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.