Chapter
11
Chapter Resources
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Chapter Summary
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Chapter Assessment Questions
Transparencies
Standardized Test Practice
Video Clips
and Animations
Chapter
11
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Chapter
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Chapter
11
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Analyzing the Energy of a Bouncing Basketball
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11
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Money Model
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11
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Throwing or Catching a Ball
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11
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Amount of Money in Various Forms
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Gravitational Potential Energy
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11
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Kinetic Energy and Potential Energy of a System
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11
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The Gravitational Potential Energy of the Bowling Ball
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11
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Arrow Moving Through the Air
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11
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Pole-vaulter Bending the Pole
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11
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System Consisting of a 10.0-N Ball and Earth
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A Ball Rolling Down a Ramp
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11
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Graph of the Changing Potential and Kinetic Energies of
a Pendulum
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11
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Energy Bar Graphs
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11
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Conservation of Mechanical Energy
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Case 1: Two Objects Moving Apart in Opposite Directions
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Case 2: Moving Object Coming to Rest and the Stationary
Object Beginning to Move and Case 3: Two Objects Sticking
Together and Moving As One
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11
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Three Kinds of Collisions
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Kinetic Energy
Chapter
11
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A Bullet Going Through a Motionless Wooden Block
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11
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A Child Sliding Down a Playground Slide
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Two Sections of Grooved Track Placed Together
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The Support Block Moved so That It Is Under the Midsection
of the Inclined Track
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11
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The Support Block Moved to a Point about Three-quarters
down the Length of the Inclined Track
Chapter
11
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Running Smarter
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Chapter Assessment (Q. 50)
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Chapter Assessment (Q. 60)
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Chapter Assessment (Q. 69)
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Chapter Assessment (Q. 71)
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Chapter Assessment (Q. 74)
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Chapter Assessment (Q. 78)
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Chapter Assessment (Q. 91)
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Standardized Test Practice (Q. 2)
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Standardized Test Practice (Q. 7)
Chapter
11
Transparencies
Chapter
11
Transparencies
Transparency 11-1
Chapter
11
Transparencies
Transparency 11-2
Chapter
11
Transparencies
Transparency 11-4
Chapter
11
Video Clips and Animations
Throwing a Ball
Chapter
11
Video Clips and Animations
Catching a Ball
Chapter
11
Video Clips and Animations
Kinetic Energy and Potential Energy of a System (1)
Chapter
11
Video Clips and Animations
Kinetic Energy and Potential Energy of a System (2)
Chapter
11
Video Clips and Animations
Gravitational Potential Energy
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Chapter
11
Video Clips and Animations
Skiing
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11
Video Clips and Animations
Pendulums
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11
Video Clips and Animations
Conservation of Mechanical Energy
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Section
11.1
Chapter Summary
The Many Forms of Energy
The kinetic energy of an object is proportional to its mass and
the square of its velocity.
The rotational kinetic energy of an object is proportional to the
object’s moment of inertia and the square of its angular velocity.
When the Earth is included in a system, the work done by
gravity is replaced by gravitational potential energy.
Section
11.1
Chapter Summary
The Many Forms of Energy
The gravitational potential energy of an object depends on the
object’s weight and its distance from Earth’s surface.
The reference level is the position where the gravitational
potential energy is defined to be zero.
Elastic potential energy may be stored in an object as a result of
its change in shape.
Section
11.1
Chapter Summary
The Many Forms of Energy
Albert Einstein recognized that mass itself has potential energy.
This energy is called rest energy.
Section
11.2
Chapter Summary
Conservation of Energy
The sum of kinetic and potential energy is called mechanical
energy.
If no objects enter or leave a system, the system is considered
to be a closed system.
If there are no external forces acting on a system, the system is
considered to be an isolated system.
Section
11.2
Chapter Summary
Conservation of Energy
The total energy of a closed, isolated system is constant. Within
the system, energy can change form, but the total amount of
energy does not change. Thus, energy is conserved.
Section
11.2
Chapter Summary
Conservation of Energy
The type of collision in which the kinetic energy after the
collision is less than the kinetic energy before the collision is
called an inelastic collision.
The type of collision in which the kinetic energy before and after
the collision is the same is called an elastic collision.
Momentum is conserved in collisions if the external force is
zero. The mechanical energy may be unchanged or decreased
by the collision, depending on whether the collision is elastic or
inelastic.
Chapter
11
Chapter Assessment Questions
Question 1
A car and a train are moving with the same velocity. Which of the
following statements about their kinetic energy is true?
A. Neither the car nor the train possesses kinetic energy.
B. Kinetic energy of the car is greater than that of the train.
C. Kinetic energy of the train is greater than that of the car.
D. Both the car and the train are running with the same kinetic
energy.
Chapter
11
Chapter Assessment Questions
Answer 1
Answer: C
Reason: Kinetic energy of an object is half times the product of its
mass and the square of its velocity.
Kinetic energy is directly proportional to mass. As the
velocity of the car and the train are the same, the train will
have greater kinetic energy since it has greater mass.
Chapter
11
Chapter Assessment Questions
Question 2
When an arrow is thrown by hand, its speed is less than the speed
when it is shot using a bow. Explain why.
Chapter
11
Chapter Assessment Questions
Answer 2
When the string of a bow is pulled, work is done on the bow. Hence,
the elastic potential energy is stored in the string of this bow. Before
the string is released, the energy is all potential. As the string is
released, the energy is transferred to the arrow as kinetic energy.
Hence, when the arrow is shot using a bow, more energy is supplied
to the system than when the arrow is thrown by hand. Hence, the
speed of the arrow is less when it is thrown by hand.
Chapter
11
Chapter Assessment Questions
Question 3
If a car is moving in the backward direction, what can we say about
its kinetic energy?
A. Kinetic energy is negative as it is moving in the backward
direction.
B. Kinetic energy is positive.
C. The car does not possess kinetic energy.
D. Kinetic energy of the car gets stored as gravitational potential
energy.
Chapter
11
Chapter Assessment Questions
Answer 3
Answer: B
Reason: Kinetic energy of an object is half the product of its mass
and the square of its velocity.
Kinetic energy is proportional to the square of velocity. Since
the square of any number is always positive, kinetic energy
is always positive.
Chapter
11
Chapter Assessment Questions
Question 4
A clock consists of an hour’s hand, a minute’s hand, and a second’s
hand all of equal masses. Which of the following statements is true?
A. Kinetic energy of the hour’s hand is greater than that of the
minute’s hand and the second’s hand.
B. Kinetic energy of the minute’s hand is greater than that of the
hour’s hand and the second’s hand.
C. Kinetic energy of the second’s hand is greater than that of the
hour’s hand and the minute’s hand.
D. All the hands are moving with equal kinetic energy.
Chapter
11
Chapter Assessment Questions
Answer 4
Answer: C
Reason: Kinetic energy of an object is half times the product of its
mass and square of its velocity.
Kinetic energy is directly proportional to velocity (speed).
Since the speed of the second’s hand is greater than the
speed of the hour’s hand and the minute’s hand and also
since the masses of all the hands are same, the kinetic
energy of the second’s hand is greater than that of the hour’s
hand and the minute’s hand.
Chapter
11
Chapter Assessment Questions
Question 5
A ball is thrown vertically upward in air. Which of the following
statements is true?
A. Kinetic energy of the ball goes on increasing.
B. Kinetic energy of the ball goes on decreasing.
C. The ball does not possess kinetic energy at all.
D. Gravitational potential energy of the ball goes on decreasing.
Chapter
11
Chapter Assessment Questions
Answer 5
Answer: B
Reason: As the ball is thrown up in the air, gravity does negative
work, slowing the ball to a stop. On the way up, as the ball
slows down, energy changes from kinetic energy to
potential energy. Therefore, the initial kinetic energy with
which the ball is thrown goes on decreasing as it gets
converted into potential energy.
Chapter
11
Chapter Assessment Questions
Question 6
A spring-loaded toy car is kept on the floor after compressing the
spring. What form of energy does the toy car use to move?
A. Stored gravitational potential energy
B. Stored kinetic energy
C. Linear kinetic energy
D. Stored elastic potential energy
Chapter
11
Chapter Assessment Questions
Answer 6
Answer: D
Reason: When a spring is compressed or stretched, or an object is
bent, energy is stored as elastic potential energy. Hence,
since the spring of the toy car is compressed, energy is
stored as elastic potential energy. The toy car uses this
stored elastic potential energy to move. As the toy car
moves, the elastic potential energy gets converted into
other forms of energy such as linear or rotational kinetic
energy.
Chapter
Standardized Test Practice
11
Multiple Choice
1.
A bicyclist increases her speed from 4.0 m/s to 6.0 m/s. The
combined mass of the bicyclist is 55 kg. How much work did the
bicyclist do in increasing her speed?
A. 11 J
B. 28 J
C. 55 J
D. 550 J
Chapter
Standardized Test Practice
11
Multiple Choice
2.
The illustration shows a ball
swinging freely in a plane.
The mass of the ball is 4.0
kg. Ignoring friction, what is
the maximum kinetic energy
of the ball as it swings back
and forth?
A. 0.14 m/s
C. 7.0 m/s
B. 21 m/s
D. 49 m/s
Chapter
Standardized Test Practice
11
Multiple Choice
3.
You lift a 4.5-kg box from the floor and place it on a shelf that is
1.5 m above the ground. How much energy did you use in lifting
the box?
A. 9.0 J
B. 49 J
C. 11 J
D. 88 J
Chapter
Standardized Test Practice
11
Multiple Choice
4.
You drop a 6.0×10−2 −kg ball from a height of 1.0 m above a hard,
flat surface. The ball strikes the surface and loses 0.14 J of its
energy. It then bounces back upward. How much kinetic energy does
the ball have just after it bounces off the flat surface?
A. 0.20 J
B. 0.59 J
C. 0.45 J
D. 0.73 J
Chapter
Standardized Test Practice
11
Multiple Choice
5.
You move a 2.5-kg book from a shelf that is 1.2 m above the ground
to a shelf that is 2.6 m above the ground. What is the change in the
book’s potential energy?
A. 1.4 J
B. 25 J
C. 3.5 J
D. 34 J
Chapter
Standardized Test Practice
11
Multiple Choice
6.
A ball of mass m rolls along a flat surface with a speed of v1. It
strikes a padded wall and bounces back in the opposite direction.
The energy of the ball after striking the wall is half its initial energy.
Ignoring friction, which of the following expressions gives the ball’s
new speed as a function of its initial speed?
A.
C.
B.
D.
Chapter
Standardized Test Practice
11
Multiple Choice
7.
The illustration to the right shows a ball
on a curved track. The ball starts with
zero velocity at the top of the track. It
then rolls from the top of the track to
the horizontal part at the ground.
Ignoring friction, its velocity just at the
moment it reaches the ground is 14
m/s. What is the height, h, from the
ground to the top of the track?
A. 7 m
C. 10 m
B. 14 m
D. 20 m
Chapter
11
Standardized Test Practice
Extended Answer
8.
A box sits on a platform supported by a compressed spring. The box
has a mass of 1.0 kg. When the spring is released, it gives 4.9 J of
energy to the box, and the box flies upward. What will be the
maximum height above the platform reached by the box before it
begins to fall?
Chapter
11
Standardized Test Practice
Test-Taking Tip
Use the Process of Elimination
On any multiple-choice test, there are two ways to find the correct
answer to each question. Either you can choose the right answer
immediately or you can eliminate the answers that you know are
wrong.
Chapter
11
Chapter Resources
End of Chapter Resource File