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Conservation Laws. Physics textbook. Contains chapter 1 - Conservation of Energy, chapter 2 - Simplifying the Energy Zoo, chapter 3 - Work: The Transfer of Mechanical Energy, chapter 4 - Conservation of Momentum, chapter 5 - Conservation of Angular Momentum, Solutions to Selected Problems, and Glossary.
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Book 2 in the Light and Matter series of free introductory physics textbooks www.lightandmatter.com
The Light and Matter series of introductory physics textbooks: 1 2 3 4 5 6
Newtonian Physics Conservation Laws Vibrations and Waves Electricity and Magnetism Optics The Modern Revolution in Physics
Benjamin Crowell
www.lightandmatter.com
Fullerton, California www.lightandmatter.com
copyright 1998-2004 Benjamin Crowell edition 2.2 rev. September 1, 2007 This book is licensed under the Creative Commons Attribution-ShareAlike license, version 1.0, http://creativecommons.org/licenses/by-sa/1.0/, except for those photographs and drawings of which I am not the author, as listed in the photo credits. If you agree to the license, it grants you certain privileges that you would not otherwise have, such as the right to copy the book, or download the digital version free of charge from www.lightandmatter.com. At your option, you may also copy this book under the GNU Free Documentation License version 1.2, http://www.gnu.org/licenses/fdl.txt, with no invariant sections, no front-cover texts, and no back-cover texts. ISBN 0-9704670-2-8
To Uri Haber-Schaim, John Dodge, Robert Gardner, and Edward Shore.
Brief Contents 1 2 3 4 5 A
Conservation of Energy 13 Simplifying the Energy Zoo 35 Work: The Transfer of Mechanical Energy 49 Conservation of Momentum 75 Conservation of Angular Momentum 105 Thermodynamics 139
Contents Problems . . . . . . . . . . . . .
45
1 Conservation of Energy 1.1 The Search for a Perpetual Motion Machine . . . . . . . . . . . . . . 13 1.2 Energy . . . . . . . . . . . .
14
1.3 A Numerical Scale of Energy . . .
18
How new forms of energy are discovered, 20.
1.4 Kinetic Energy . . . . . . . . .
3 Work: The Transfer of Mechanical Energy 3.1 Work: The Transfer of Mechanical Energy . . . . . . . . . . . . . . 49 The concept of work, 49.—Calculating work as force multiplied by distance, 50.— Machines can increase force, but not work., 52.—No work is done without motion., 52.—Positive and negative work, 53.
23
Energy and relative motion, 24.
1.5 Power . . . . . . . . . . . . .
26
Summary . . . . . . . . . . . . .
28
Problems . . . . . . . . . . . . .
30
3.2 Work in Three Dimensions . . . .
2.1 Heat is Kinetic Energy . . . . . .
36
2.2 Potential Energy: Energy of Distance or Closeness . . . . . . . . . . . . 38
. . . . . . . . .
58
Applications of Calculus . . . .
61
3.5 Work and Potential Energy . . . .
62
3.4
R
3.6 ? When Does Work Equal Force Times Distance? . . . . . . . . . . 65
An equation for gravitational potential energy, 39.
10
A force perpendicular to the motion does no work., 56.—Forces at other angles, 56.
3.3 Varying Force
2 Simplifying the Energy Zoo
56
2.3 All Energy is Potential or Kinetic . .
42
3.7 ? The Dot Product . . . . . . . .
67
Summary . . . . . . . . . . . . .
44
Summary . . . . . . . . . . . . .
68
Problems . . . . . . . . . . . . .
70
5 Conservation Momentum
of
Angular
5.1 Conservation of Angular Momentum 107 Restriction to rotation in a plane, 111.
5.2 Angular Mo