Solution Manual for Physics: for Scientists and Engineers with Modern Physics, 3rd Edition
Get immediate access to clear and precise solutions with Solution Manual for Physics: for Scientists and Engineers with Modern Physics, 3rd Edition.
Chloe Martinez
Contributor
4.7
136
4 months ago
Preview (31 of 1291)
Sign in to access the full document!
I N S T R U C T O R
S O L U T I O N S M A N U A L
T H I R D E D I T I O N
physicsF O R S C I E N T I S T S A N D E N G I N E E R S
a strategic approach
randall d. knight
Larry Smith
Snow College
Brett Kraabel
PhD-Physics, University of Santa Barbara
Boston Columbus Indianapolis New York San Francisco Upper Saddle River
Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto
Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo
S O L U T I O N S M A N U A L
T H I R D E D I T I O N
physicsF O R S C I E N T I S T S A N D E N G I N E E R S
a strategic approach
randall d. knight
Larry Smith
Snow College
Brett Kraabel
PhD-Physics, University of Santa Barbara
Boston Columbus Indianapolis New York San Francisco Upper Saddle River
Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto
Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo
I N S T R U C T O R
S O L U T I O N S M A N U A L
T H I R D E D I T I O N
physicsF O R S C I E N T I S T S A N D E N G I N E E R S
a strategic approach
randall d. knight
Larry Smith
Snow College
Brett Kraabel
PhD-Physics, University of Santa Barbara
Boston Columbus Indianapolis New York San Francisco Upper Saddle River
Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto
Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo
S O L U T I O N S M A N U A L
T H I R D E D I T I O N
physicsF O R S C I E N T I S T S A N D E N G I N E E R S
a strategic approach
randall d. knight
Larry Smith
Snow College
Brett Kraabel
PhD-Physics, University of Santa Barbara
Boston Columbus Indianapolis New York San Francisco Upper Saddle River
Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto
Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo
Publisher: James Smith
Senior Development Editor: Alice Houston, Ph.D.
Senior Project Editor: Martha Steele
Assistant Editor: Peter Alston
Media Producer: Kelly Reed
Senior Administrative Assistant: Cathy Glenn
Director of Marketing: Christy Lesko
Executive Marketing Manager: Kerry McGinnis
Managing Editor: Corinne Benson
Production Project Manager: Beth Collins
Production Management, Illustration, and Composition: PreMediaGlobal, Inc.
Copyright ©2013, 2008, 2004 Pearson Education, Inc. All rights reserved. Manufactured in the United States
of America. This publication is protected by Copyright, and permission should be obtained from the publisher
prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means,
electronic, mechanical, photocopying, recording, or likewise. To obtain permission(s) to use material from this
work, please submit a written request to Pearson Education, Inc., Permissions Department, 1900 E. Lake Ave.,
Glenview, IL 60025. For information regarding permissions, call (847) 486-2635.
Many of the designations used by manufacturers and sellers to distinguish their products are claimed as
trademarks. Where those designations appear in this book, and the publisher was aware of a trademark claim,
the designations have been printed in initial caps or all caps.
MasteringPhysics is a trademark, in the U.S. and/or other countries, of Pearson Education, Inc. or its affiliates.
ISBN 13: 978-0-321-76940-4
ISBN 10: 0-321-76940-6
www.pearsonhighered.com
Senior Development Editor: Alice Houston, Ph.D.
Senior Project Editor: Martha Steele
Assistant Editor: Peter Alston
Media Producer: Kelly Reed
Senior Administrative Assistant: Cathy Glenn
Director of Marketing: Christy Lesko
Executive Marketing Manager: Kerry McGinnis
Managing Editor: Corinne Benson
Production Project Manager: Beth Collins
Production Management, Illustration, and Composition: PreMediaGlobal, Inc.
Copyright ©2013, 2008, 2004 Pearson Education, Inc. All rights reserved. Manufactured in the United States
of America. This publication is protected by Copyright, and permission should be obtained from the publisher
prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means,
electronic, mechanical, photocopying, recording, or likewise. To obtain permission(s) to use material from this
work, please submit a written request to Pearson Education, Inc., Permissions Department, 1900 E. Lake Ave.,
Glenview, IL 60025. For information regarding permissions, call (847) 486-2635.
Many of the designations used by manufacturers and sellers to distinguish their products are claimed as
trademarks. Where those designations appear in this book, and the publisher was aware of a trademark claim,
the designations have been printed in initial caps or all caps.
MasteringPhysics is a trademark, in the U.S. and/or other countries, of Pearson Education, Inc. or its affiliates.
ISBN 13: 978-0-321-76940-4
ISBN 10: 0-321-76940-6
www.pearsonhighered.com
Contents
Preface ....................................................................................................................................... v
PART I Newton’s Laws
Chapter 1 Concepts of Motion.............................................................................................. 1-1
Chapter 2 Kinematics in One Dimension ............................................................................. 2-1
Chapter 3 Vectors and Coordinate Systems ......................................................................... 3-1
Chapter 4 Kinematics in Two Dimensions ........................................................................... 4-1
Chapter 5 Force and Motion ................................................................................................. 5-1
Chapter 6 Dynamics I: Motion Along a Line ....................................................................... 6-1
Chapter 7 Newton’s Third Law ............................................................................................ 7-1
Chapter 8 Dynamics II: Motion in a Plane ........................................................................... 8-1
PART II Conservation Laws
Chapter 9 Impulse and Momentum ...................................................................................... 9-1
Chapter 10 Energy ................................................................................................................ 10-1
Chapter 11 Work .................................................................................................................. 11-1
PART III Applications of Newtonian Mechanics
Chapter 12 Rotation of a Rigid Body ................................................................................... 12-1
Chapter 13 Newton’s Theory of Gravity .............................................................................. 13-1
Chapter 14 Oscillations ........................................................................................................ 14-1
Chapter 15 Fluids and Elasticity........................................................................................... 15-1
PART IV Thermodynamics
Chapter 16 A Macroscopic Description of Matter ............................................................... 16-1
Chapter 17 Work, Heat, and the First Law of Thermodynamics.......................................... 17-1
Chapter 18 The Micro/Macro Connection............................................................................ 18-1
Chapter 19 Heat Engines and Refrigerators ......................................................................... 19-1
Preface ....................................................................................................................................... v
PART I Newton’s Laws
Chapter 1 Concepts of Motion.............................................................................................. 1-1
Chapter 2 Kinematics in One Dimension ............................................................................. 2-1
Chapter 3 Vectors and Coordinate Systems ......................................................................... 3-1
Chapter 4 Kinematics in Two Dimensions ........................................................................... 4-1
Chapter 5 Force and Motion ................................................................................................. 5-1
Chapter 6 Dynamics I: Motion Along a Line ....................................................................... 6-1
Chapter 7 Newton’s Third Law ............................................................................................ 7-1
Chapter 8 Dynamics II: Motion in a Plane ........................................................................... 8-1
PART II Conservation Laws
Chapter 9 Impulse and Momentum ...................................................................................... 9-1
Chapter 10 Energy ................................................................................................................ 10-1
Chapter 11 Work .................................................................................................................. 11-1
PART III Applications of Newtonian Mechanics
Chapter 12 Rotation of a Rigid Body ................................................................................... 12-1
Chapter 13 Newton’s Theory of Gravity .............................................................................. 13-1
Chapter 14 Oscillations ........................................................................................................ 14-1
Chapter 15 Fluids and Elasticity........................................................................................... 15-1
PART IV Thermodynamics
Chapter 16 A Macroscopic Description of Matter ............................................................... 16-1
Chapter 17 Work, Heat, and the First Law of Thermodynamics.......................................... 17-1
Chapter 18 The Micro/Macro Connection............................................................................ 18-1
Chapter 19 Heat Engines and Refrigerators ......................................................................... 19-1
iv C O N T E N T S
Chapter 20 Traveling Waves ................................................................................................ 20-1
Chapter 21 Superposition ..................................................................................................... 21-1
Chapter 22 Wave Optics ....................................................................................................... 22-1
Chapter 23 Ray Optics.......................................................................................................... 23-1
Chapter 24 Optical Instruments ............................................................................................ 24-1
PART VI Electricity and Magnetism
Chapter 25 Electric Charges and Forces............................................................................... 25-1
Chapter 26 The Electric Field............................................................................................... 26-1
Chapter 27 Gauss’s Law....................................................................................................... 27-1
Chapter 28 The Electric Potential......................................................................................... 28-1
Chapter 29 Potential and Field ............................................................................................. 29-1
Chapter 30 Current and Resistance ...................................................................................... 30-1
Chapter 31 Fundamentals of Circuits ................................................................................... 31-1
Chapter 32 The Magnetic Field ............................................................................................ 32-1
Chapter 33 Electromagnetic Induction ................................................................................. 33-1
Chapter 34 Electromagnetic Fields and Waves .................................................................... 34-1
Chapter 35 AC Circuits ........................................................................................................ 35-1
PART VII Relativity and Quantum Physics
Chapter 36 Relativity............................................................................................................ 36-1
Chapter 37 The Foundations of Modern Physics ................................................................. 37-1
Chapter 38 Quantization ....................................................................................................... 38-1
Chapter 39 Wave Functions and Uncertainty ....................................................................... 39-1
Chapter 40 One-Dimensional Quantum Mechanics ............................................................. 40-1
Chapter 41 Atomic Physics .................................................................................................. 41-1
Chapter 42 Nuclear Physics.................................................................................................. 42-1
PART V Waves and Optics
Chapter 20 Traveling Waves ................................................................................................ 20-1
Chapter 21 Superposition ..................................................................................................... 21-1
Chapter 22 Wave Optics ....................................................................................................... 22-1
Chapter 23 Ray Optics.......................................................................................................... 23-1
Chapter 24 Optical Instruments ............................................................................................ 24-1
PART VI Electricity and Magnetism
Chapter 25 Electric Charges and Forces............................................................................... 25-1
Chapter 26 The Electric Field............................................................................................... 26-1
Chapter 27 Gauss’s Law....................................................................................................... 27-1
Chapter 28 The Electric Potential......................................................................................... 28-1
Chapter 29 Potential and Field ............................................................................................. 29-1
Chapter 30 Current and Resistance ...................................................................................... 30-1
Chapter 31 Fundamentals of Circuits ................................................................................... 31-1
Chapter 32 The Magnetic Field ............................................................................................ 32-1
Chapter 33 Electromagnetic Induction ................................................................................. 33-1
Chapter 34 Electromagnetic Fields and Waves .................................................................... 34-1
Chapter 35 AC Circuits ........................................................................................................ 35-1
PART VII Relativity and Quantum Physics
Chapter 36 Relativity............................................................................................................ 36-1
Chapter 37 The Foundations of Modern Physics ................................................................. 37-1
Chapter 38 Quantization ....................................................................................................... 38-1
Chapter 39 Wave Functions and Uncertainty ....................................................................... 39-1
Chapter 40 One-Dimensional Quantum Mechanics ............................................................. 40-1
Chapter 41 Atomic Physics .................................................................................................. 41-1
Chapter 42 Nuclear Physics.................................................................................................. 42-1
PART V Waves and Optics
Preface
This Instructor Solutions Manual has a twofold purpose. First, and most obvious, is to pro-
vide worked solutions for the use of instructors. Second, but equally important, is to provide
examples of good problem-solving techniques and strategies that will benefit your students if
you post these solutions.
Far too many solutions manuals simply plug numbers into equations, thereby reinforcing one
of the worst student habits. The solutions provided here, by contrast, attempt to:
• Follow, in detail, the problem-solving strategies presented in the text.
• Articulate the reasoning that must be done before computation.
• Illustrate how to use drawings effectively.
• Demonstrate how to utilize graphs, ratios, units, and the many other “tactics” that must be
successfully mastered and marshaled if a problem-solving strategy is to be effective.
• Show examples of assessing the reasonableness of a solution.
• Comment on the significance of a solution or on its relationship to other problems.
Most education researchers believe that it is more beneficial for students to study a smaller
number of carefully chosen problems in detail, including variations, than to race through a
larger number of poorly understood calculations. The solutions presented here are intended
to provide a basis for this practice.
So that you may readily edit and/or post these solutions, they are available for download as
editable Word documents and as pdf files via the “Resources” tab in the textbook’s Instruc-
tor Resource Center (www.pearsonhighered.com/educator/catalog/index.page) or from the
textbook’s Instructor Resource Area in MasteringPhysics® (www.masteringphysics.com).
We have made every effort to be accurate and correct in these solutions. However, if you do
find errors or ambiguities, we would be very grateful to hear from you. Please contact your
Pearson Education sales representative.
This Instructor Solutions Manual has a twofold purpose. First, and most obvious, is to pro-
vide worked solutions for the use of instructors. Second, but equally important, is to provide
examples of good problem-solving techniques and strategies that will benefit your students if
you post these solutions.
Far too many solutions manuals simply plug numbers into equations, thereby reinforcing one
of the worst student habits. The solutions provided here, by contrast, attempt to:
• Follow, in detail, the problem-solving strategies presented in the text.
• Articulate the reasoning that must be done before computation.
• Illustrate how to use drawings effectively.
• Demonstrate how to utilize graphs, ratios, units, and the many other “tactics” that must be
successfully mastered and marshaled if a problem-solving strategy is to be effective.
• Show examples of assessing the reasonableness of a solution.
• Comment on the significance of a solution or on its relationship to other problems.
Most education researchers believe that it is more beneficial for students to study a smaller
number of carefully chosen problems in detail, including variations, than to race through a
larger number of poorly understood calculations. The solutions presented here are intended
to provide a basis for this practice.
So that you may readily edit and/or post these solutions, they are available for download as
editable Word documents and as pdf files via the “Resources” tab in the textbook’s Instruc-
tor Resource Center (www.pearsonhighered.com/educator/catalog/index.page) or from the
textbook’s Instructor Resource Area in MasteringPhysics® (www.masteringphysics.com).
We have made every effort to be accurate and correct in these solutions. However, if you do
find errors or ambiguities, we would be very grateful to hear from you. Please contact your
Pearson Education sales representative.
Loading page 6...
vi P R E F A C E
Acknowledgments for the First Edition
We are grateful for many helpful comments from Susan Cable, Randall Knight, and Steve
Stonebraker. We express appreciation to Susan Emerson, who typed the word-processing
manuscript, for her diligence in interpreting our handwritten copy. Finally, we would like to
acknowledge the support from the Addison Wesley staff in getting the work into a publisha-
ble state. Our special thanks to Liana Allday, Alice Houston, and Sue Kimber for their will-
ingness and preparedness in providing needed help at all times.
Pawan Kahol
Missouri State University
Donald Foster
Wichita State University
Acknowledgments for the Second Edition
I would like to acknowledge the patient support of my wife, Holly, who knows what is im-
portant.
Larry Smith
Snow College
I would like to acknowledge the assistance and support of my wife, Alice Nutter, who helped
type many problems and was patient while I worked weekends.
Scott Nutter
Northern Kentucky University
Acknowledgments for the Third Edition
To Holly, Ryan, Timothy, Nathan, Tessa, and Tyler, who make it all worthwhile.
Larry Smith
Snow College
I gratefully acknowledge the assistance of the staff at Physical Sciences Communication.
Brett Kraabel
PhD-University of Santa Barbara
Acknowledgments for the First Edition
We are grateful for many helpful comments from Susan Cable, Randall Knight, and Steve
Stonebraker. We express appreciation to Susan Emerson, who typed the word-processing
manuscript, for her diligence in interpreting our handwritten copy. Finally, we would like to
acknowledge the support from the Addison Wesley staff in getting the work into a publisha-
ble state. Our special thanks to Liana Allday, Alice Houston, and Sue Kimber for their will-
ingness and preparedness in providing needed help at all times.
Pawan Kahol
Missouri State University
Donald Foster
Wichita State University
Acknowledgments for the Second Edition
I would like to acknowledge the patient support of my wife, Holly, who knows what is im-
portant.
Larry Smith
Snow College
I would like to acknowledge the assistance and support of my wife, Alice Nutter, who helped
type many problems and was patient while I worked weekends.
Scott Nutter
Northern Kentucky University
Acknowledgments for the Third Edition
To Holly, Ryan, Timothy, Nathan, Tessa, and Tyler, who make it all worthwhile.
Larry Smith
Snow College
I gratefully acknowledge the assistance of the staff at Physical Sciences Communication.
Brett Kraabel
PhD-University of Santa Barbara
Loading page 7...
Conceptual Questions
1.1. (a) 3 significant figures.
(b) 2 significant figures. This is more clearly revealed by using scientific notation:2 sig. figs.
1
0.53 5.3 10−
=
(c) 4 significant figures. The trailing zero is significant because it indicates increased precision.
(d) 3 significant figures. The leading zeros are not significant but just locate the decimal point.
1.2. (a) 2 significant figures. Trailing zeros in front of the decimal point merely locate the decimal point and are
not significant.
(b) 3 significant figures. Trailing zeros after the decimal point are significant because they indicate increased
precision.
(c) 4 significant figures.
(d) 3 significant figures. Trailing zeros after the decimal point are significant because they indicate increased
precision.
1.3. Without numbers on the dots we cannot tell if the particle in the figure is moving left or right, so we can’t tell
if it is speeding up or slowing down. If the particle is moving to the right it is slowing down. If it is moving to the left
it is speeding up.
1.4. Because the velocity vectors get longer for each time step, the object must be speeding up as it travels to the
left. The acceleration vector must therefore point in the same direction as the velocity, so the acceleration vector also
points to the left. Thus,xa is negative as per our convention (see Tactics Box 1.4).
1.5. Because the velocity vectors get shorter for each time step, the object must be slowing down as it travels in
they2 direction (down). The acceleration vector must therefore point in the direction opposite to the velocity;
namely, in the +y direction (up). Thus,ya is positive as per our convention (see Tactics Box 1.4).
1.6. The particle position is to the left of zero on the x-axis, so its position is negative. The particle is moving to the
right, so its velocity is positive. The particle’s speed is increasing as it moves to the right, so its acceleration vector
points in the same direction as its velocity vector (i.e., to the right). Thus, the acceleration is also positive.
1.7. The particle position is below zero on the y-axis, so its position is negative. The particle is moving down, so
its velocity is negative. The particle’s speed is increasing as it moves in the negative direction, so its acceleration
vector points in the same direction as its velocity vector (i.e., down). Thus, the acceleration is also negative.
CONCEPTS OF MOTION
1
1.1. (a) 3 significant figures.
(b) 2 significant figures. This is more clearly revealed by using scientific notation:2 sig. figs.
1
0.53 5.3 10−
=
(c) 4 significant figures. The trailing zero is significant because it indicates increased precision.
(d) 3 significant figures. The leading zeros are not significant but just locate the decimal point.
1.2. (a) 2 significant figures. Trailing zeros in front of the decimal point merely locate the decimal point and are
not significant.
(b) 3 significant figures. Trailing zeros after the decimal point are significant because they indicate increased
precision.
(c) 4 significant figures.
(d) 3 significant figures. Trailing zeros after the decimal point are significant because they indicate increased
precision.
1.3. Without numbers on the dots we cannot tell if the particle in the figure is moving left or right, so we can’t tell
if it is speeding up or slowing down. If the particle is moving to the right it is slowing down. If it is moving to the left
it is speeding up.
1.4. Because the velocity vectors get longer for each time step, the object must be speeding up as it travels to the
left. The acceleration vector must therefore point in the same direction as the velocity, so the acceleration vector also
points to the left. Thus,xa is negative as per our convention (see Tactics Box 1.4).
1.5. Because the velocity vectors get shorter for each time step, the object must be slowing down as it travels in
they2 direction (down). The acceleration vector must therefore point in the direction opposite to the velocity;
namely, in the +y direction (up). Thus,ya is positive as per our convention (see Tactics Box 1.4).
1.6. The particle position is to the left of zero on the x-axis, so its position is negative. The particle is moving to the
right, so its velocity is positive. The particle’s speed is increasing as it moves to the right, so its acceleration vector
points in the same direction as its velocity vector (i.e., to the right). Thus, the acceleration is also positive.
1.7. The particle position is below zero on the y-axis, so its position is negative. The particle is moving down, so
its velocity is negative. The particle’s speed is increasing as it moves in the negative direction, so its acceleration
vector points in the same direction as its velocity vector (i.e., down). Thus, the acceleration is also negative.
CONCEPTS OF MOTION
1
Loading page 8...
1-2 Chapter 1
1.8. The particle position is above zero on the y-axis, so its position is positive. The particle is moving down, so its
velocity is negative. The particle’s speed is increasing as it moves in the negative direction, so its acceleration vector
points in the same direction as its velocity vector (i.e., down). Thus, the acceleration is also negative.
Exercises and Problems
Section 1.1 Motion Diagrams
1.1. Model: Imagine a car moving in the positive direction (i.e., to the right). As it skids, it covers less distance
between each movie frame (or between each snapshot).
Solve:
Assess: As we go from left to right, the distance between successive images of the car decreases. Because the time
interval between each successive image is the same, the car must be slowing down.
1.2. Model: We have no information about the acceleration of the rocket, so we will assume that it accelerates
upward with a constant acceleration.
Solve:
Assess: Notice that the length of the velocity vectors increases each step by approximately the length of the
acceleration vector.
1.8. The particle position is above zero on the y-axis, so its position is positive. The particle is moving down, so its
velocity is negative. The particle’s speed is increasing as it moves in the negative direction, so its acceleration vector
points in the same direction as its velocity vector (i.e., down). Thus, the acceleration is also negative.
Exercises and Problems
Section 1.1 Motion Diagrams
1.1. Model: Imagine a car moving in the positive direction (i.e., to the right). As it skids, it covers less distance
between each movie frame (or between each snapshot).
Solve:
Assess: As we go from left to right, the distance between successive images of the car decreases. Because the time
interval between each successive image is the same, the car must be slowing down.
1.2. Model: We have no information about the acceleration of the rocket, so we will assume that it accelerates
upward with a constant acceleration.
Solve:
Assess: Notice that the length of the velocity vectors increases each step by approximately the length of the
acceleration vector.
Loading page 9...
Concepts of Motion 1-3
1.3. Model: We will assume that the term “quickly” used in the problem statement means a time that is short
compared to 30 s.
Solve:
Assess: Notice that the acceleration vector points in the direction opposite to the velocity vector because the car is
decelerating.
Section 1.2 The Particle Model
1.4. Solve: (a) The basic idea of the particle model is that we will treat an object as if all its mass is concentrated
into a single point. The size and shape of the object will not be considered. This is a reasonable approximation of
reality if (i) the distance traveled by the object is large in comparison to the size of the object and (ii) rotations and
internal motions are not significant features of the object’s motion. The particle model is important in that it allows
us to simplify a problem. Complete reality—which would have to include the motion of every single atom in the
object—is too complicated to analyze. By treating an object as a particle, we can focus on the most important aspects
of its motion while neglecting minor and unobservable details.
(b) The particle model is valid for understanding the motion of a satellite or a car traveling a large distance.
(c) The particle model is not valid for understanding how a car engine operates, how a person walks, how a bird flies,
or how water flows through a pipe.
Section 1.3 Position and Time
Section 1.4 Velocity
1.5. Model: We model the ball’s motion from the instant after it is released, when it has zero velocity, to the
instant before it hits the ground, when it will have its maximum velocity.
Solve:
1.3. Model: We will assume that the term “quickly” used in the problem statement means a time that is short
compared to 30 s.
Solve:
Assess: Notice that the acceleration vector points in the direction opposite to the velocity vector because the car is
decelerating.
Section 1.2 The Particle Model
1.4. Solve: (a) The basic idea of the particle model is that we will treat an object as if all its mass is concentrated
into a single point. The size and shape of the object will not be considered. This is a reasonable approximation of
reality if (i) the distance traveled by the object is large in comparison to the size of the object and (ii) rotations and
internal motions are not significant features of the object’s motion. The particle model is important in that it allows
us to simplify a problem. Complete reality—which would have to include the motion of every single atom in the
object—is too complicated to analyze. By treating an object as a particle, we can focus on the most important aspects
of its motion while neglecting minor and unobservable details.
(b) The particle model is valid for understanding the motion of a satellite or a car traveling a large distance.
(c) The particle model is not valid for understanding how a car engine operates, how a person walks, how a bird flies,
or how water flows through a pipe.
Section 1.3 Position and Time
Section 1.4 Velocity
1.5. Model: We model the ball’s motion from the instant after it is released, when it has zero velocity, to the
instant before it hits the ground, when it will have its maximum velocity.
Solve:
Loading page 10...
1-4 Chapter 1
Assess: Notice that the “particle” we have drawn has a finite dimensions, so it appears as if the bottom half of this
“particle” has penetrated into the ground in the bottom frame. This is not really the case; our mental particle has no
size and is located at the tip of the velocity vector arrow.
1.6. Solve: The player starts from rest and moves faster and faster.
1.7. Solve: The player starts with an initial velocity but as he slides he moves slower and slower until coming to rest.
Section 1.5 Linear Acceleration
1.8. Solve: (a) Let0v be the velocity vector between points 0 and 1 and1v be the velocity vector between points
1 and 2. Speed1v is greater than speed0v because more distance is covered in the same interval of time.
(b) To find the acceleration, use the method of Tactics Box 1.3:
Assess: The acceleration vector points in the same direction as the velocity vectors, which makes sense because the
speed is increasing.
1.9. Solve: (a) Let0v be the velocity vector between points 0 and 1 and1v be the velocity vector between points 1
and 2. Speed1v is greater than speed0v because more distance is covered in the same interval of time.
(b) Acceleration is found by the method of Tactics Box 1.3.
Assess: The acceleration vector points in the same direction as the velocity vectors, which makes sense because the
speed is increasing.
Assess: Notice that the “particle” we have drawn has a finite dimensions, so it appears as if the bottom half of this
“particle” has penetrated into the ground in the bottom frame. This is not really the case; our mental particle has no
size and is located at the tip of the velocity vector arrow.
1.6. Solve: The player starts from rest and moves faster and faster.
1.7. Solve: The player starts with an initial velocity but as he slides he moves slower and slower until coming to rest.
Section 1.5 Linear Acceleration
1.8. Solve: (a) Let0v be the velocity vector between points 0 and 1 and1v be the velocity vector between points
1 and 2. Speed1v is greater than speed0v because more distance is covered in the same interval of time.
(b) To find the acceleration, use the method of Tactics Box 1.3:
Assess: The acceleration vector points in the same direction as the velocity vectors, which makes sense because the
speed is increasing.
1.9. Solve: (a) Let0v be the velocity vector between points 0 and 1 and1v be the velocity vector between points 1
and 2. Speed1v is greater than speed0v because more distance is covered in the same interval of time.
(b) Acceleration is found by the method of Tactics Box 1.3.
Assess: The acceleration vector points in the same direction as the velocity vectors, which makes sense because the
speed is increasing.
Loading page 11...
Concepts of Motion 1-5
1.10. Solve:
(a) (b)
1.11. Solve:
(a) (b)
1.12. Model: Represent the car as a particle.
Visualize: The dots are equally spaced until brakes are applied to the car. Equidistant dots on a single line indicate
constant average velocity. Upon braking, the dots get closer as the average velocity decreases, and the distance
between dots changes by a constant amount because the acceleration is constant.
1.13. Model: Represent the (child + sled) system as a particle.
Visualize: The dots in the figure are equally spaced until the sled encounters a rocky patch. Equidistant dots on a
single line indicate constant average velocity. On encountering a rocky patch, the average velocity decreases and the
sled comes to a stop. This part of the motion is indicated by a decreasing separation between the dots.
1.14. Model: Represent the wad of paper as a particle. Ignore air resistance.
1.10. Solve:
(a) (b)
1.11. Solve:
(a) (b)
1.12. Model: Represent the car as a particle.
Visualize: The dots are equally spaced until brakes are applied to the car. Equidistant dots on a single line indicate
constant average velocity. Upon braking, the dots get closer as the average velocity decreases, and the distance
between dots changes by a constant amount because the acceleration is constant.
1.13. Model: Represent the (child + sled) system as a particle.
Visualize: The dots in the figure are equally spaced until the sled encounters a rocky patch. Equidistant dots on a
single line indicate constant average velocity. On encountering a rocky patch, the average velocity decreases and the
sled comes to a stop. This part of the motion is indicated by a decreasing separation between the dots.
1.14. Model: Represent the wad of paper as a particle. Ignore air resistance.
Loading page 12...
1-6 Chapter 1
Visualize: The dots become more closely spaced because the particle experiences a downward acceleration. The
distance between dots changes by a constant amount because the acceleration is constant.
1.15. Model: Represent the tile as a particle.
Visualize: Starting from rest, the tile’s velocity increases until it hits the water surface. This part of the motion is
represented by dots with increasing separation, indicating increasing average velocity. After the tile enters the water,
it settles to the bottom at roughly constant speed, so this part of the motion is represented by equally spaced dots.
1.16. Model: Represent the tennis ball as a particle.
Visualize: The ball falls freely for three stories. Upon impact, it quickly decelerates to zero velocity while comp-
ressing, then accelerates rapidly while re-expanding. As vectors, both the deceleration and acceleration are an upward
vector. The downward and upward motions of the ball are shown separately in the figure. The increasing length between
the dots during downward motion indicates an increasing average velocity or downward acceleration. On the other hand,
the decreasing length between the dots during upward motion indicates acceleration in a direction opposite to the
motion, so the average velocity decreases.
Assess: For free-fall motion, acceleration due to gravity is always vertically downward. Notice that the acceleration
due to the ground is quite large (although not to scale—that would take too much space) because in a time interval
much shorter than the time interval between the points, the velocity of the ball is essentially completely reversed.
Visualize: The dots become more closely spaced because the particle experiences a downward acceleration. The
distance between dots changes by a constant amount because the acceleration is constant.
1.15. Model: Represent the tile as a particle.
Visualize: Starting from rest, the tile’s velocity increases until it hits the water surface. This part of the motion is
represented by dots with increasing separation, indicating increasing average velocity. After the tile enters the water,
it settles to the bottom at roughly constant speed, so this part of the motion is represented by equally spaced dots.
1.16. Model: Represent the tennis ball as a particle.
Visualize: The ball falls freely for three stories. Upon impact, it quickly decelerates to zero velocity while comp-
ressing, then accelerates rapidly while re-expanding. As vectors, both the deceleration and acceleration are an upward
vector. The downward and upward motions of the ball are shown separately in the figure. The increasing length between
the dots during downward motion indicates an increasing average velocity or downward acceleration. On the other hand,
the decreasing length between the dots during upward motion indicates acceleration in a direction opposite to the
motion, so the average velocity decreases.
Assess: For free-fall motion, acceleration due to gravity is always vertically downward. Notice that the acceleration
due to the ground is quite large (although not to scale—that would take too much space) because in a time interval
much shorter than the time interval between the points, the velocity of the ball is essentially completely reversed.
Loading page 13...
Concepts of Motion 1-7
1.17. Model: Represent the toy car as a particle.
Visualize: As the toy car rolls down the ramp, its speed increases. This is indicated by the increasing length of the
velocity arrows. That is, motion down the ramp is under a constant accelerationa At the bottom of the ramp, the toy
car continues with a constant velocity and no acceleration.
Section 1.6 Motion in One Dimension
1.18. Solve:
(a) Dot Time (s) x (m) (b)
1 0 0
2 2 30
3 4 95
4 6 215
5 8 400
6 10 510
7 12 600
8 14 670
9 16 720
1.19. Solve: A forgetful physics professor is walking from one class to the next. Walking at a constant speed, he
covers a distance of 100 m in 200 s. He then stops and chats with a student for 200 s. Suddenly, he realizes he is
going to be late for his next class, so the hurries on and covers the remaining 200 m in 200 s to get to class on time.
1.20. Solve: Forty miles into a car trip north from his home in El Dorado, an absent-minded English professor
stopped at a rest area one Saturday. After staying there for one hour, he headed back home thinking that he was
supposed to go on this trip on Sunday. Absent-mindedly he missed his exit and stopped after one hour of driving at
another rest area 20 miles south of El Dorado. After waiting there for one hour, he drove back very slowly, confused
and tired as he was, and reached El Dorado two hours later.
Section 1.7 Solving Problems in Physics
1.21. Visualize: The bicycle move forward with an acceleration of2
1.5 m/s . Thus, the velocity will increase by
1.5 m/s each second of motion.
1.17. Model: Represent the toy car as a particle.
Visualize: As the toy car rolls down the ramp, its speed increases. This is indicated by the increasing length of the
velocity arrows. That is, motion down the ramp is under a constant accelerationa At the bottom of the ramp, the toy
car continues with a constant velocity and no acceleration.
Section 1.6 Motion in One Dimension
1.18. Solve:
(a) Dot Time (s) x (m) (b)
1 0 0
2 2 30
3 4 95
4 6 215
5 8 400
6 10 510
7 12 600
8 14 670
9 16 720
1.19. Solve: A forgetful physics professor is walking from one class to the next. Walking at a constant speed, he
covers a distance of 100 m in 200 s. He then stops and chats with a student for 200 s. Suddenly, he realizes he is
going to be late for his next class, so the hurries on and covers the remaining 200 m in 200 s to get to class on time.
1.20. Solve: Forty miles into a car trip north from his home in El Dorado, an absent-minded English professor
stopped at a rest area one Saturday. After staying there for one hour, he headed back home thinking that he was
supposed to go on this trip on Sunday. Absent-mindedly he missed his exit and stopped after one hour of driving at
another rest area 20 miles south of El Dorado. After waiting there for one hour, he drove back very slowly, confused
and tired as he was, and reached El Dorado two hours later.
Section 1.7 Solving Problems in Physics
1.21. Visualize: The bicycle move forward with an acceleration of2
1.5 m/s . Thus, the velocity will increase by
1.5 m/s each second of motion.
Loading page 14...
1-8 Chapter 1
1.22. Visualize: The rocket moves upward with a constant acceleration.a The final velocity is 200 m/s and is
reached at a height of 1.0 km.
Section 1.8 Units and Significant Figures
1.23. Solve: (a)3
3
1s
6.15 ms (6 15 ms) 6.15 10 s
10 ms
−
= =
(b)3 310 m
27.2 km (27 2 km) 27.2 10 m
1 km
= =
(c)3
km 10 m 1 hour
112 km/hour 112 31.1 m/s
hour 1 km 3600 s
= =
(d)3 2
6
m 1 m 10
1.22. Visualize: The rocket moves upward with a constant acceleration.a The final velocity is 200 m/s and is
reached at a height of 1.0 km.
Section 1.8 Units and Significant Figures
1.23. Solve: (a)3
3
1s
6.15 ms (6 15 ms) 6.15 10 s
10 ms
−
= =
(b)3 310 m
27.2 km (27 2 km) 27.2 10 m
1 km
= =
(c)3
km 10 m 1 hour
112 km/hour 112 31.1 m/s
hour 1 km 3600 s
= =
(d)3 2
6
m 1 m 10
Loading page 15...
Loading page 16...
1-10 Chapter 1
1.31. Solve: The height of a telephone pole is estimated to be around 50 ft or (using 1 m ~ 3 ft) about 15 m. This
height is approximately 8 times my height.
1.32. Solve: I typically take 15 minutes in my car to cover a distance of approximately 6 miles from home to
campus. My average speed is6 miles 60 min 0.447 m/s
24 mph (24 mph) 11 m/s
15 min 1 hour 1 mph
= = =
1.33. Solve: My barber trims about an inch of hair when I visit him every month for a haircut. The rate of hair
growth is2 9
6
9
1inch 2.54 cm 10 m 1 month 1 day 1 h 9.8 10 m/s
1 month 1 inch 1 cm 30 days 24 h 3600 s
m 10 m 3600 s
9.8 10 40 m/h
s 1 m 1 h
− −
−
=
=
1.34. Model: Represent the Porsche as a particle for the motion diagram. Assume the car moves at a constant
speed when it coasts.
Visualize:
1.35. Model: Represent the jet as a particle for the motion diagram.
Visualize:
1.31. Solve: The height of a telephone pole is estimated to be around 50 ft or (using 1 m ~ 3 ft) about 15 m. This
height is approximately 8 times my height.
1.32. Solve: I typically take 15 minutes in my car to cover a distance of approximately 6 miles from home to
campus. My average speed is6 miles 60 min 0.447 m/s
24 mph (24 mph) 11 m/s
15 min 1 hour 1 mph
= = =
1.33. Solve: My barber trims about an inch of hair when I visit him every month for a haircut. The rate of hair
growth is2 9
6
9
1inch 2.54 cm 10 m 1 month 1 day 1 h 9.8 10 m/s
1 month 1 inch 1 cm 30 days 24 h 3600 s
m 10 m 3600 s
9.8 10 40 m/h
s 1 m 1 h
− −
−
=
=
1.34. Model: Represent the Porsche as a particle for the motion diagram. Assume the car moves at a constant
speed when it coasts.
Visualize:
1.35. Model: Represent the jet as a particle for the motion diagram.
Visualize:
Loading page 17...
Concepts of Motion 1-11
1.36. Model: Represent (Sam + car) as a particle for the motion diagram.
Visualize:
1.37. Model: Represent the wad as a particle for the motion diagram.
Visualize:
1.36. Model: Represent (Sam + car) as a particle for the motion diagram.
Visualize:
1.37. Model: Represent the wad as a particle for the motion diagram.
Visualize:
Loading page 18...
1-12 Chapter 1
1.38. Model: Represent the speed skater as a particle for the motion diagram.
Visualize:
1.39. Model: Represent Santa Claus as a particle for the motion diagram.
Visualize:
1.38. Model: Represent the speed skater as a particle for the motion diagram.
Visualize:
1.39. Model: Represent Santa Claus as a particle for the motion diagram.
Visualize:
Loading page 19...
Concepts of Motion 1-13
1.40. Model: Represent the motorist as a particle for the motion diagram.
Visualize:
1.41. Model: Represent the car as a particle for the motion diagram.
Visualize:
1.42. Model: Represent Bruce and the puck as particles for the motion diagram.
Visualize:
1.40. Model: Represent the motorist as a particle for the motion diagram.
Visualize:
1.41. Model: Represent the car as a particle for the motion diagram.
Visualize:
1.42. Model: Represent Bruce and the puck as particles for the motion diagram.
Visualize:
Loading page 20...
1-14 Chapter 1
1.43. Model: Represent the cars of David and Tina and as particles for the motion diagram.
Visualize:
1.44. Solve: Isabel is the first car in line at a stop light. When it turns green, she accelerates, hoping to make the
next stop light 100 m away before it turns red. When she’s about 30 m away, the light turns yellow, so she starts to
brake, knowing that she cannot make the light.
1.45. Solve: A car coasts along at 30 m/s and arrives at a hill. The car decelerates as it coasts up the hill. At the
top, the road levels and the car continues coasting along the road at a reduced speed.
1.46. Solve: A skier starts from rest down a 25° slope with very little friction. At the bottom of the 100-m slope
the terrain becomes flat and the skier continues at constant velocity.
1.47. Solve: A ball is dropped from a height to check its rebound properties. It rebounds to 80% of its original
height.
1.48. Solve: Two boards lean against each other at equal angles to the vertical direction. A ball rolls up the
incline, over the peak, and down the other side.
1.49. Solve:
(a)
(b) A train moving at 100 km/hour slows down in 10 s to a speed of 60 km/hour as it enters a tunnel. The driver
maintains this constant speed for the entire length of the tunnel that takes the train a time of 20 s to traverse. Find the
length of the tunnel.
1.43. Model: Represent the cars of David and Tina and as particles for the motion diagram.
Visualize:
1.44. Solve: Isabel is the first car in line at a stop light. When it turns green, she accelerates, hoping to make the
next stop light 100 m away before it turns red. When she’s about 30 m away, the light turns yellow, so she starts to
brake, knowing that she cannot make the light.
1.45. Solve: A car coasts along at 30 m/s and arrives at a hill. The car decelerates as it coasts up the hill. At the
top, the road levels and the car continues coasting along the road at a reduced speed.
1.46. Solve: A skier starts from rest down a 25° slope with very little friction. At the bottom of the 100-m slope
the terrain becomes flat and the skier continues at constant velocity.
1.47. Solve: A ball is dropped from a height to check its rebound properties. It rebounds to 80% of its original
height.
1.48. Solve: Two boards lean against each other at equal angles to the vertical direction. A ball rolls up the
incline, over the peak, and down the other side.
1.49. Solve:
(a)
(b) A train moving at 100 km/hour slows down in 10 s to a speed of 60 km/hour as it enters a tunnel. The driver
maintains this constant speed for the entire length of the tunnel that takes the train a time of 20 s to traverse. Find the
length of the tunnel.
Loading page 21...
Concepts of Motion 1-15
(c)
1.50. Solve:
(a)
(b) Sue passes 3rd Street doing 30 km/h, slows steadily to the stop sign at 4th Street, stops for 1.0 s, then speeds up
and reaches her original speed as she passes 5th Street. If the blocks are 50 m long, how long does it take Sue to drive
from 3rd Street to 5th Street?
(c)
1.51. Solve:
(a)
(b) Jeremy has perfected the art of steady acceleration and deceleration. From a speed of 60 mph he brakes his car to
rest in 10 s with a constant deceleration. Then he turns into an adjoining street. Starting from rest, Jeremy accelerates
with exactly the same magnitude as his earlier deceleration and reaches the same speed of 60 mph over the same
distance in exactly the same time. Find the car’s acceleration or deceleration.
(c)
1.50. Solve:
(a)
(b) Sue passes 3rd Street doing 30 km/h, slows steadily to the stop sign at 4th Street, stops for 1.0 s, then speeds up
and reaches her original speed as she passes 5th Street. If the blocks are 50 m long, how long does it take Sue to drive
from 3rd Street to 5th Street?
(c)
1.51. Solve:
(a)
(b) Jeremy has perfected the art of steady acceleration and deceleration. From a speed of 60 mph he brakes his car to
rest in 10 s with a constant deceleration. Then he turns into an adjoining street. Starting from rest, Jeremy accelerates
with exactly the same magnitude as his earlier deceleration and reaches the same speed of 60 mph over the same
distance in exactly the same time. Find the car’s acceleration or deceleration.
Loading page 22...
1-16 Chapter 1
(c)
1.52. Solve:
(a)
(b) A coyote (A) sees a rabbit and begins to run toward it with an acceleration of 3.02
m/s . At the same instant, the
rabbit (B) begins to run away from the coyote with an acceleration of 2.02
m/s . The coyote catches the rabbit after
running 40 m. How far away was the rabbit when the coyote first saw it?
(c)
1.53. Solve: Since area equals length3 width, the smallest area will correspond to the smaller length and the
smaller width. Similarly, the largest area will correspond to the larger length and the larger width. Therefore, the
smallest area is (64 m)(100 m) = 6.43 2
10 m3 and the largest area is (75 m)(110 m) = 8.333 2
10 m .
1.54. Solve: (a) We need3
kg/m . There are 100 cm in 1 m. If we multiply by3 3100 cm (1)
1 m
=
we do not change the size of the quantity, but only the number in terms of the new unit. Thus, the mass density of
aluminum is3
3 3
3 3
kg 100 cm kg
2.7 10 2.7 10
1 mcm m
−
=
(c)
1.52. Solve:
(a)
(b) A coyote (A) sees a rabbit and begins to run toward it with an acceleration of 3.02
m/s . At the same instant, the
rabbit (B) begins to run away from the coyote with an acceleration of 2.02
m/s . The coyote catches the rabbit after
running 40 m. How far away was the rabbit when the coyote first saw it?
(c)
1.53. Solve: Since area equals length3 width, the smallest area will correspond to the smaller length and the
smaller width. Similarly, the largest area will correspond to the larger length and the larger width. Therefore, the
smallest area is (64 m)(100 m) = 6.43 2
10 m3 and the largest area is (75 m)(110 m) = 8.333 2
10 m .
1.54. Solve: (a) We need3
kg/m . There are 100 cm in 1 m. If we multiply by3 3100 cm (1)
1 m
=
we do not change the size of the quantity, but only the number in terms of the new unit. Thus, the mass density of
aluminum is3
3 3
3 3
kg 100 cm kg
2.7 10 2.7 10
1 mcm m
−
=
Loading page 23...
Concepts of Motion 1-17
(b) Likewise, the mass density of alcohol is3
3 3
g 100 cm 1 kg kg
0.81 810
1 m 1000 gcm m
=
1.55. Model: In the particle model, the car is represented as a dot.
Solve:
(a) Time t (s) Position x (m) (b)
0 1200
10 975
20 825
30 750
40 700
50 650
60 600
70 500
80 300
90 0
1.56. Solve: Susan enters a classroom, sees a seat 40 m directly ahead, and begins walking toward it at a constant
leisurely pace, covering the first 10 m in 10 seconds. But then Susan notices that Ella is heading toward the same
seat, so Susan walks more quickly to cover the remaining 30 m in another 10 seconds, beating Ella to the seat. Susan
stands next to the seat for 10 seconds to remove her backpack.
1.57. Solve: A crane operator starts lifting a ton of bricks off the ground. In 8 s, he has lifted them to a height of
15 m, then he takes 4 s to make a safety check. He then continues raising the bricks the remaining 15 m, which takes 4 s.
(b) Likewise, the mass density of alcohol is3
3 3
g 100 cm 1 kg kg
0.81 810
1 m 1000 gcm m
=
1.55. Model: In the particle model, the car is represented as a dot.
Solve:
(a) Time t (s) Position x (m) (b)
0 1200
10 975
20 825
30 750
40 700
50 650
60 600
70 500
80 300
90 0
1.56. Solve: Susan enters a classroom, sees a seat 40 m directly ahead, and begins walking toward it at a constant
leisurely pace, covering the first 10 m in 10 seconds. But then Susan notices that Ella is heading toward the same
seat, so Susan walks more quickly to cover the remaining 30 m in another 10 seconds, beating Ella to the seat. Susan
stands next to the seat for 10 seconds to remove her backpack.
1.57. Solve: A crane operator starts lifting a ton of bricks off the ground. In 8 s, he has lifted them to a height of
15 m, then he takes 4 s to make a safety check. He then continues raising the bricks the remaining 15 m, which takes 4 s.
Loading page 24...
Loading page 25...
Conceptual Questions
2.1. It was a typical summer day on the interstate. I started 10 mi east of town and drove for 20 min at 30 mph west
to town. My stop for gas took 10 min. Then I headed back east at 60 mph before I encountered a construction zone.
Traffic was at a standstill for 10 min and then I was able to move forward (east) at 30 mph until I got to my
destination 30 mi east of town.
2.2. With a slow start out of the blocks, a super sprinter reached top speed in about 5 s, having gone only 30 m. He
was still able to finish his 100 m in only just over 9 s by running a world record pace for the rest of the race.
2.3. The baseball team is warming up. The pitcher (who is 50 feet from home plate) lobs the ball at 100 ft/s to the
second baseman who is 100 ft from home plate. The second baseman then fires the ball at 200 ft/s to the catcher at
home plate.
2.4. (a) At1 s,t = the slope of the line for object A is greater than that for object B. Therefore, object A’s speed is
greater. (Both are positive slopes.)
(b) No, the speeds are never the same. Each has a constant speed (constant slope) and A’s speed is always greater.
2.5. (a) A’s speed is greater at1 s.t = The slope of the tangent to B’s curve at1 st = is smaller than the slope of
A’s line.
(b) A and B have the same speed at just about3 s.t = At that time, the slope of the tangent to the curve representing
B’s motion is equal to the slope of the line representing A.
2.6. (a) B. The object is still moving, but the magnitude of the slope of the position-versus-time curve is smaller than at D.
(b) D. The slope is greatest at D.
(c) At points A, C, and E the slope of the curve is zero, so the object is not moving.
(d) At point D the slope is negative, so the object is moving to the left.
2.7. (a) The slope of the position-versus-time graph is greatest at D, so the object is moving fastest at this point.
(b) The slope is negative at points C, D, and E, meaning the object is moving to the left at these points.
(c) At point C the slope is increasing in magnitude (getting more negative), meaning that the object is speeding up to
the left.
(d) At point B the object is not moving since the slope is zero. Before point B, the slope is positive, while after B it is
negative, so the object is turning around at B.
2.8. (a) The positions of the third dots of both motion diagrams are the same, as are the sixth dots of both, so cars A
and B are at the same locations at the time corresponding to dot 3 and again at that of dot 6.
(b) The spacing of dots 4 and 5 in both diagrams is the same, so the cars are traveling at the same speeds between
times corresponding to dots 4 and 5.
KINEMATICS IN ONE DIMENSION
2
2.1. It was a typical summer day on the interstate. I started 10 mi east of town and drove for 20 min at 30 mph west
to town. My stop for gas took 10 min. Then I headed back east at 60 mph before I encountered a construction zone.
Traffic was at a standstill for 10 min and then I was able to move forward (east) at 30 mph until I got to my
destination 30 mi east of town.
2.2. With a slow start out of the blocks, a super sprinter reached top speed in about 5 s, having gone only 30 m. He
was still able to finish his 100 m in only just over 9 s by running a world record pace for the rest of the race.
2.3. The baseball team is warming up. The pitcher (who is 50 feet from home plate) lobs the ball at 100 ft/s to the
second baseman who is 100 ft from home plate. The second baseman then fires the ball at 200 ft/s to the catcher at
home plate.
2.4. (a) At1 s,t = the slope of the line for object A is greater than that for object B. Therefore, object A’s speed is
greater. (Both are positive slopes.)
(b) No, the speeds are never the same. Each has a constant speed (constant slope) and A’s speed is always greater.
2.5. (a) A’s speed is greater at1 s.t = The slope of the tangent to B’s curve at1 st = is smaller than the slope of
A’s line.
(b) A and B have the same speed at just about3 s.t = At that time, the slope of the tangent to the curve representing
B’s motion is equal to the slope of the line representing A.
2.6. (a) B. The object is still moving, but the magnitude of the slope of the position-versus-time curve is smaller than at D.
(b) D. The slope is greatest at D.
(c) At points A, C, and E the slope of the curve is zero, so the object is not moving.
(d) At point D the slope is negative, so the object is moving to the left.
2.7. (a) The slope of the position-versus-time graph is greatest at D, so the object is moving fastest at this point.
(b) The slope is negative at points C, D, and E, meaning the object is moving to the left at these points.
(c) At point C the slope is increasing in magnitude (getting more negative), meaning that the object is speeding up to
the left.
(d) At point B the object is not moving since the slope is zero. Before point B, the slope is positive, while after B it is
negative, so the object is turning around at B.
2.8. (a) The positions of the third dots of both motion diagrams are the same, as are the sixth dots of both, so cars A
and B are at the same locations at the time corresponding to dot 3 and again at that of dot 6.
(b) The spacing of dots 4 and 5 in both diagrams is the same, so the cars are traveling at the same speeds between
times corresponding to dots 4 and 5.
KINEMATICS IN ONE DIMENSION
2
Loading page 26...
2-2 Chapter 2
2.9. No, though you have the same position along the road, his velocity is greater because he is passing you. If his
velocity were not greater, then he would remain even with the front of your car.
2.10. Yes. The acceleration vector will point west when the bicycle is slowing down while traveling east.
2.11. (a) As a ball tossed upward moves upward, its vertical velocity is positive, while its vertical acceleration is
negative, opposite the velocity, causing the ball to slow down.
(b) The same ball on its way down has downward (negative) velocity. The downward negative acceleration is
pointing in the same direction as the velocity, causing the speed to increase.
2.12. For all three of these situations the acceleration is equal to g in the downward direction. The magnitude and
direction of the velocity of the ball do not matter. Gravity pulls down at constant acceleration. (Air friction is
ignored.)
2.13. (a) The magnitude of the acceleration while in free fall is equal to g at all times, independent of the initial
velocity. The acceleration only tells how the velocity is changing.
(b) The magnitude of the acceleration is still g because the rock is still in free fall. The speed is increasing at the same
rate each instant, that is, by the samev each second.
2.14. The ball remains in contact with the floor for a small but noticeable amount of time. It is in free fall when not
in contact with the floor. When it hits the floor, it is accelerated very rapidly in the upward direction as it bounces.
2.9. No, though you have the same position along the road, his velocity is greater because he is passing you. If his
velocity were not greater, then he would remain even with the front of your car.
2.10. Yes. The acceleration vector will point west when the bicycle is slowing down while traveling east.
2.11. (a) As a ball tossed upward moves upward, its vertical velocity is positive, while its vertical acceleration is
negative, opposite the velocity, causing the ball to slow down.
(b) The same ball on its way down has downward (negative) velocity. The downward negative acceleration is
pointing in the same direction as the velocity, causing the speed to increase.
2.12. For all three of these situations the acceleration is equal to g in the downward direction. The magnitude and
direction of the velocity of the ball do not matter. Gravity pulls down at constant acceleration. (Air friction is
ignored.)
2.13. (a) The magnitude of the acceleration while in free fall is equal to g at all times, independent of the initial
velocity. The acceleration only tells how the velocity is changing.
(b) The magnitude of the acceleration is still g because the rock is still in free fall. The speed is increasing at the same
rate each instant, that is, by the samev each second.
2.14. The ball remains in contact with the floor for a small but noticeable amount of time. It is in free fall when not
in contact with the floor. When it hits the floor, it is accelerated very rapidly in the upward direction as it bounces.
Loading page 27...
Kinematics in One Dimension 2-3
Exercises and Problems
Section 2.1 Uniform Motion
2.1. Model: Cars will be treated by the particle model.
Visualize:
Solve: Beth and Alan are moving at a constant speed, so we can calculate the time of arrival as follows:1 0 1 0
1 0
1 0
x x x x x
v t t
t t t v
− −
= = = +
−
Using the known values identified in the pictorial representation, we find:Alan 1 Alan 0
Alan 1 Alan 0
Beth 1 Beth 0
Beth 1 Beth 0
400 mile
8:00 AM 8:00 AM 8 hr 4:00 PM
50 miles/hour
400 mile
9:00 AM 9:00 AM 6.67 hr 3:40 PM
60 miles/hour
x x
t t v
x x
t t v
−
= + = + = + =
−
= + = + = + =
(a) Beth arrives first.
(b) Beth has to waitAlan 1 Beth 1 20 minutest t− = for Alan.
Assess: Times of the order of 7 or 8 hours are reasonable in the present problem.
2.2. Model: We will consider Larry to be a particle.
Visualize:
Exercises and Problems
Section 2.1 Uniform Motion
2.1. Model: Cars will be treated by the particle model.
Visualize:
Solve: Beth and Alan are moving at a constant speed, so we can calculate the time of arrival as follows:1 0 1 0
1 0
1 0
x x x x x
v t t
t t t v
− −
= = = +
−
Using the known values identified in the pictorial representation, we find:Alan 1 Alan 0
Alan 1 Alan 0
Beth 1 Beth 0
Beth 1 Beth 0
400 mile
8:00 AM 8:00 AM 8 hr 4:00 PM
50 miles/hour
400 mile
9:00 AM 9:00 AM 6.67 hr 3:40 PM
60 miles/hour
x x
t t v
x x
t t v
−
= + = + = + =
−
= + = + = + =
(a) Beth arrives first.
(b) Beth has to waitAlan 1 Beth 1 20 minutest t− = for Alan.
Assess: Times of the order of 7 or 8 hours are reasonable in the present problem.
2.2. Model: We will consider Larry to be a particle.
Visualize:
Loading page 28...
Loading page 29...
Kinematics in One Dimension 2-5
(b) There is only one turning point. At1 st = the velocity changes from20 m/s+ to5 m/s,− thus reversing the direction
of motion. At3 s,t = there is an abrupt change in motion from5 m/s− to rest, but there is no reversal in motion.
2.6. Visualize: Please refer to Figure EX2.6. The particle starts at0 10 mx = at0 0.t = Its velocity is initially in
the –x direction. The speed decreases as time increases during the first second, is zero at
(b) There is only one turning point. At1 st = the velocity changes from20 m/s+ to5 m/s,− thus reversing the direction
of motion. At3 s,t = there is an abrupt change in motion from5 m/s− to rest, but there is no reversal in motion.
2.6. Visualize: Please refer to Figure EX2.6. The particle starts at0 10 mx = at0 0.t = Its velocity is initially in
the –x direction. The speed decreases as time increases during the first second, is zero at
Loading page 30...
Loading page 31...
30 more pages available. Scroll down to load them.
Preview Mode
Sign in to access the full document!
100%
Study Now!
XY-Copilot AI
Unlimited Access
Secure Payment
Instant Access
24/7 Support
Document Chat
Document Details
Subject
Physics