Halliday/Resnick/Walker

Fundamentals of Physics 8th edition

Classroom Response System Questions

Chapter 7 Kinetic Energy and Work

Reading Questions

7.2.1. Which one of the following statements concerning the principle of the

conservation of energy is true?

a) Energy is neither created nor destroyed, but its total amount remains

constant.

b) If more people use less energy, the Earth’s resources would last longer.

c) Energy may be created as needed and transformed into various forms.

d) There have only been a few situations that have been discovered in which

the principle of the conservation of energy is violated.

e) The energy that moving objects have is destroyed by frictional forces as

they slow down.

7.2.1. Which one of the following statements concerning the principle of the

conservation of energy is true?

a) Energy is neither created nor destroyed, but its total amount remains

constant.

b) If more people use less energy, the Earth’s resources would last longer.

c) Energy may be created as needed and transformed into various forms.

d) There have only been a few situations that have been discovered in which

the principle of the conservation of energy is violated.

e) The energy that moving objects have is destroyed by frictional forces as

they slow down.

7.2.2. According to the text, what is the technical definition of energy?

This was described in the section entitled, “What is energy?”

a) Energy is a vector quantity, similar to time, that flows in only one

direction.

b) Energy is a way of quantifying the motion of an object.

c) Energy is that which propels objects into motion.

d) Energy is a scalar quantity associated with the state (or condition)

of one or more objects.

e) Energy is a universal element that is contained within all objects

and may be transformed into either objects or motion.

7.2.2. According to the text, what is the technical definition of energy?

This was described in the section entitled, “What is energy?”

a) Energy is a vector quantity, similar to time, that flows in only one

direction.

b) Energy is a way of quantifying the motion of an object.

c) Energy is that which propels objects into motion.

d) Energy is a scalar quantity associated with the state (or condition)

of one or more objects.

e) Energy is a universal element that is contained within all objects

and may be transformed into either objects or motion.

7.3.1. Which one of the following statements concerning kinetic

energy is true?

a) The kinetic energy of an object is directly proportional to its speed.

b) The kinetic energy of an object is expressed in watts.

c) The kinetic energy of an object is a quantitative measure of its

inertia.

d) The kinetic energy of an object always has a positive value.

e) The kinetic energy of an object is always equal to the object’s total

energy.

7.3.1. Which one of the following statements concerning kinetic

energy is true?

a) The kinetic energy of an object is directly proportional to its speed.

b) The kinetic energy of an object is expressed in watts.

c) The kinetic energy of an object is a quantitative measure of its

inertia.

d) The kinetic energy of an object always has a positive value.

e) The kinetic energy of an object is always equal to the object’s total

energy.

7.3.2. Which one of the following is an example of an object

with a non-zero kinetic energy?

a) a train is parked in a train station

b) a car rests at the top of a hill

c) the pendulum of a grandfather clock is still

d) a boulder rests at the bottom of a cliff

e) the international space station is orbiting the Earth

7.3.2. Which one of the following is an example of an object

with a non-zero kinetic energy?

a) a train is parked in a train station

b) a car rests at the top of a hill

c) the pendulum of a grandfather clock is still

d) a boulder rests at the bottom of a cliff

e) the international space station is orbiting the Earth

7.3.3. In which one of the following situations will there be an

increase in kinetic energy?

a) A kicked football approaches its maximum height as it passes

through the goal posts.

b) The planet Venus moves in its nearly circular orbit around the Sun.

c) A fan is switched from “low speed” to “high speed.”

d) A filing cabinet is pushed across a rough floor at constant speed.

e) A train is pulled up a mountain at a constant speed by a motor.

7.3.3. In which one of the following situations will there be an

increase in kinetic energy?

a) A kicked football approaches its maximum height as it passes

through the goal posts.

b) The planet Venus moves in its nearly circular orbit around the Sun.

c) A fan is switched from “low speed” to “high speed.”

d) A filing cabinet is pushed across a rough floor at constant speed.

e) A train is pulled up a mountain at a constant speed by a motor.

7.3.4. Which one of the following expressions is equal to the kinetic

energy of an object?

a) mvt2

b)

c) Fd cos

d) ma

e) mgh

212

mv

7.3.4. Which one of the following expressions is equal to the kinetic

energy of an object?

a) mvt2

b)

c) Fd cos

d) ma

e) mgh

212

mv

7.3.5. Which one of the following combinations of units is equal to the

joule?

a) kg m2/s

b) kg m

c) kg m/s

d) kg m2/s2

e) kg s

7.3.5. Which one of the following combinations of units is equal to the

joule?

a) kg m2/s

b) kg m

c) kg m/s

d) kg m2/s2

e) kg s

7.3.6. The graph below shows the velocity of

an object as a function of time. Which of

the graph of kinetic energy versus time

matches the velocity data?

7.3.6. The graph below shows the velocity of

an object as a function of time. Which of

the graph of kinetic energy versus time

matches the velocity data?

7.4.1. Which one of the following statements is the correct description

of the term work as described in the text?

a) Work is energy exerted over time to increase or decrease the

motion of an object.

b) Work is the power required to increase or decrease the motion of an

object.

c) Work is the force that produces energy.

d) Work is the force that transfers energy to or from an object.

e) Work is energy transferred to or from an object by means of a force

acting on the object.

7.4.1. Which one of the following statements is the correct description

of the term work as described in the text?

a) Work is energy exerted over time to increase or decrease the

motion of an object.

b) Work is the power required to increase or decrease the motion of an

object.

c) Work is the force that produces energy.

d) Work is the force that transfers energy to or from an object.

e) Work is energy transferred to or from an object by means of a force

acting on the object.

7.5.1. In which one of the following situations is zero net work done?

a) A bunch of bananas is placed on a spring scale in a supermarket.

b) A sky diver falls from an airplane and considers when to open her

parachute.

c) A horse pulls a wagon at a constant velocity.

d) A snowball rolls down a hill.

e) A skateboarder steps on a skateboard, which begins to roll.

7.5.1. In which one of the following situations is zero net work done?

a) A bunch of bananas is placed on a spring scale in a supermarket.

b) A sky diver falls from an airplane and considers when to open her

parachute.

c) A horse pulls a wagon at a constant velocity.

d) A snowball rolls down a hill.

e) A skateboarder steps on a skateboard, which begins to roll.

7.5.2. A 5.0-kg ball on the end of a chain is whirled at a constant speed

of 1.0 m/s in a horizontal circle of radius 3.0 m. What is the work

done by the centripetal force during one revolution?

a) 2.5 J

b) 1.7 J

c) 1.2 J

d) 0.56 J

e) zero J

7.5.2. A 5.0-kg ball on the end of a chain is whirled at a constant speed

of 1.0 m/s in a horizontal circle of radius 3.0 m. What is the work

done by the centripetal force during one revolution?

a) 2.5 J

b) 1.7 J

c) 1.2 J

d) 0.56 J

e) zero J

7.5.3. In which of the following circumstances does the force do positive

work on the object?

a) The direction of the force is perpendicular to the object’s displacement.

b) The direction of the force is in the opposite direction to the object’s

displacement.

c) No matter the direction of the force, positive work will be done if there is

a displacement of the object.

d) The direction of the force is in the same direction as the object’s

displacement.

e) The object’s displacement is zero meters as the force is applied.

7.5.3. In which of the following circumstances does the force do positive

work on the object?

a) The direction of the force is perpendicular to the object’s displacement.

b) The direction of the force is in the opposite direction to the object’s

displacement.

c) No matter the direction of the force, positive work will be done if there is

a displacement of the object.

d) The direction of the force is in the same direction as the object’s

displacement.

e) The object’s displacement is zero meters as the force is applied.

7.5.4. Complete the following statement: If positive work is done on a

moving object,

a) the velocity of the object will increase.

b) the velocity of the object will decrease.

c) the kinetic energy of the object will decrease.

d) the velocity of the object will not change.

e) the direction of the acceleration of the object will be opposite to its

displacement.

7.5.4. Complete the following statement: If positive work is done on a

moving object,

a) the velocity of the object will increase.

b) the velocity of the object will decrease.

c) the kinetic energy of the object will decrease.

d) the velocity of the object will not change.

e) the direction of the acceleration of the object will be opposite to its

displacement.

7.5.5. Which one of the following expressions results in the same units

as those for work? In the following m represents mass, x

represents distance, a represents acceleration, v represents speed,

and t represents time.

a) mvt

b) xvt

c) xat

d) mx/t

e) mat

7.5.5. Which one of the following expressions results in the same units

as those for work? In the following m represents mass, x

represents distance, a represents acceleration, v represents speed,

and t represents time.

a) mvt

b) xvt

c) xat

d) mx/t

e) mat

7.6.1. 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

7.6.1. 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

7.6.2. A man lifts a 100-N table to a height of 0.4 m above the floor.

Suddenly, he loses grip and the table drops down to the floor.

What is the total work done on the table?

a) zero joules

b) 20 J

c) 40 J

d) 80 J

e) 100 J

7.6.2. A man lifts a 100-N table to a height of 0.4 m above the floor.

Suddenly, he loses grip and the table drops down to the floor.

What is the total work done on the table?

a) zero joules

b) 20 J

c) 40 J

d) 80 J

e) 100 J

7.6.3. Alice and Bill, who happen to have the same mass, both want to climb to the

top of a mountain. Bill wants to take the steep path straight up, but Alice wants

to take the path that gently winds around the mountain, even though it is 8 times

longer than the steep path. They both eventually reach the top of the mountain,

but Alice reaches the top in 1/3 the time that Bill takes using the steep route.

How does the work that Alice did in climbing the mountain compare with the

amount that Bill did?

a) Alice did 1/8 the amount of work that Bill did.

b) Alice did 1/3 the amount of work that Bill did.

c) Alice and Bill did the same amount of work.

d) Alice did twice the amount of work that Bill did.

e) Alice did three times the amount of work that Bill did.

7.6.3. Alice and Bill, who happen to have the same mass, both want to climb to the

top of a mountain. Bill wants to take the steep path straight up, but Alice wants

to take the path that gently winds around the mountain, even though it is 8 times

longer than the steep path. They both eventually reach the top of the mountain,

but Alice reaches the top in 1/3 the time that Bill takes using the steep route.

How does the work that Alice did in climbing the mountain compare with the

amount that Bill did?

a) Alice did 1/8 the amount of work that Bill did.

b) Alice did 1/3 the amount of work that Bill did.

c) Alice and Bill did the same amount of work.

d) Alice did twice the amount of work that Bill did.

e) Alice did three times the amount of work that Bill did.

7.6.4. Sara carries a heavy box of books down a flight of stairs from the third

floor to the first floor. Which one of the following statements best

describes the work done on the box by Sara?

a) Sara doesn’t do any work on the heavy box of books.

b) Sara does a small amount of negative work on the heavy box of books.

c) Sara does a small amount of positive work on the heavy box of books.

d) Sara does a large amount of negative work on the heavy box of books.

e) Sara does a large amount of positive work on the heavy box of books.

7.6.4. Sara carries a heavy box of books down a flight of stairs from the third

floor to the first floor. Which one of the following statements best

describes the work done on the box by Sara?

a) Sara doesn’t do any work on the heavy box of books.

b) Sara does a small amount of negative work on the heavy box of books.

c) Sara does a small amount of positive work on the heavy box of books.

d) Sara does a large amount of negative work on the heavy box of books.

e) Sara does a large amount of positive work on the heavy box of books.

7.6.5. Sara carries a heavy box of books down a flight of stairs from the third

floor to the first floor. Which one of the following statements best

describes the work done on the box by the Earth’s gravity?

a) Gravity doesn’t do any work on the heavy box of books.

b) Gravity does a small amount of negative work on the heavy box of books.

c) Gravity does a small amount of positive work on the heavy box of books.

d) Gravity does a large amount of negative work on the heavy box of books.

e) Gravity does a large amount of positive work on the heavy box of books.

7.6.5. Sara carries a heavy box of books down a flight of stairs from the third

floor to the first floor. Which one of the following statements best

describes the work done on the box by the Earth’s gravity?

a) Gravity doesn’t do any work on the heavy box of books.

b) Gravity does a small amount of negative work on the heavy box of books.

c) Gravity does a small amount of positive work on the heavy box of books.

d) Gravity does a large amount of negative work on the heavy box of books.

e) Gravity does a large amount of positive work on the heavy box of books.

7.7.1. An object that obeys Hooke’s law is displaced a distance x by a

net force Which one of the following statements correctly

describes the resulting acceleration of the object?

a) The magnitude of the acceleration is constant.

b) The acceleration increases as x increases and it decreases as x

decreases.

c) The acceleration is always in the positive x direction.

d) The acceleration is only dependent on the mass of the object.

e) The acceleration increases as x decreases and decreases as x

increases.

7.7.1. An object that obeys Hooke’s law is displaced a distance x by a

net force Which one of the following statements correctly

describes the resulting acceleration of the object?

a) The magnitude of the acceleration is constant.

b) The acceleration increases as x increases and it decreases as x

decreases.

c) The acceleration is always in the positive x direction.

d) The acceleration is only dependent on the mass of the object.

e) The acceleration increases as x decreases and decreases as x

increases.

7.7.2. A block is hung vertically at the end of a spring. When the

block is displaced and released, it moves in simple harmonic

motion. Which one of the following statements is true concerning

the block?

a) The maximum acceleration of the block occurs when its velocity is

zero.

b) The velocity of the block is never zero m/s.

c) If the velocity of the block is zero m/s, it acceleration is zero m/s2.

d) The maximum velocity occurs when the maximum acceleration

occurs.

7.7.2. A block is hung vertically at the end of a spring. When the

block is displaced and released, it moves in simple harmonic

motion. Which one of the following statements is true concerning

the block?

a) The maximum acceleration of the block occurs when its velocity is

zero.

b) The velocity of the block is never zero m/s.

c) If the velocity of the block is zero m/s, it acceleration is zero m/s2.

d) The maximum velocity occurs when the maximum acceleration

occurs.

7.7.3. What is the work done in stretching a spring by a

distance of 0.5 m if the restoring force is 24 N?

a) 3 J

b) 6 J

c) 9 J

d) 12 J

e) 24 J

7.7.3. What is the work done in stretching a spring by a

distance of 0.5 m if the restoring force is 24 N?

a) 3 J

b) 6 J

c) 9 J

d) 12 J

e) 24 J

7.7.4. What is the value of the spring constant of a spring

that is stretched a distance of 0.5 m if the restoring force

is 24 N?

a) 6 N/m

b) 12 N/m

c) 18 N/m

d) 24 N/m

e) 48 N/m

7.7.4. What is the value of the spring constant of a spring

that is stretched a distance of 0.5 m if the restoring force

is 24 N?

a) 6 N/m

b) 12 N/m

c) 18 N/m

d) 24 N/m

e) 48 N/m

7.7.5. A spring is attached to a block. Complete the following

statement: The work done by the spring on the block

a) depends on the mass of the block.

b) is positive when the spring is compressed.

c) is positive when the spring is stretched.

d) is always negative.

e) depends on the distance the spring is stretched from its relaxed

position.

7.7.5. A spring is attached to a block. Complete the following

statement: The work done by the spring on the block

a) depends on the mass of the block.

b) is positive when the spring is compressed.

c) is positive when the spring is stretched.

d) is always negative.

e) depends on the distance the spring is stretched from its relaxed

position.

7.8.1. The work done by a force that varies in magnitude can be

obtained from which of the following choices?

a) by calculating the average force and multiplying by the

displacement

b) by finding the area under a force versus velocity graph

c) by integrating Fdx

d) by finding the area under a force versus displacement graph

e) by either choice (c) or choice (d)

7.8.1. The work done by a force that varies in magnitude can be

obtained from which of the following choices?

a) by calculating the average force and multiplying by the

displacement

b) by finding the area under a force versus velocity graph

c) by integrating Fdx

d) by finding the area under a force versus displacement graph

e) by either choice (c) or choice (d)

7.9.1. Which one of the following choices is not a unit of

power?

a) kg m2/s

b) ft lb/s

c) horsepower

d) J/s

e) W

7.9.1. Which one of the following choices is not a unit of

power?

a) kg m2/s

b) ft lb/s

c) horsepower

d) J/s

e) W

7.9.2. The power due to a force depends on which of the following

parameters?

a) the magnitude of the force and the displacement of the object

b) the magnitude of the force and the velocity of the object

c) the mass of the object and the velocity of the object

d) the work done on the object and its displacement

e) the mass of the object and the displacement of the object

7.9.2. The power due to a force depends on which of the following

parameters?

a) the magnitude of the force and the displacement of the object

b) the magnitude of the force and the velocity of the object

c) the mass of the object and the velocity of the object

d) the work done on the object and its displacement

e) the mass of the object and the displacement of the object

7.9.3. The position of a crate sliding across

a frictionless surface is plotted as a

function of time in the graph below.

Which of the force versus distance

graphs shown corresponds to this

situation?

7.9.3. The position of a crate sliding across

a frictionless surface is plotted as a

function of time in the graph below.

Which of the force versus distance

graphs shown corresponds to this

situation?