Instructor’s Manual for FUNDAMENTALS OF PHYSICS Seventh Edition by David Halliday, Robert Resnick, and Jearl Walker Prepared by J. Richard Christman Professor Emeritus United States Coast Guard Academy with the assistance of Stanley A. Williams Iowa State University Walter Eppenstein Rensselaer Polytechnic Institute PREFACE This manual contains material designed to be useful in the design of an introductory physics course based on the text FUNDAMENTALS OF PHYSICS, seventh edition, by David Halliday, Robert Resnick, and Jearl Walker. It may be used with either the extended or regular versions of the text. Section One includes material to help instructors choose topics and design courses. Section Two contains a discussion of sources for ancillary material that might be helpful in designing a course or obtaining lab and demonstration apparatus and audio/visual material. Section Three contains lecture notes outlining the important topics of each chapter, suggested demonstration and laboratory experiments, computer software, video cassettes, and DVDs. Sections Four, Five, and Six contain answers to checkpoints, end-of-chapter questions, and end- of-chapter problems. To help ease the transition from the sixth to the seventh edition of the text, Section Seven of the manual cross references end-of-chapter problems between the two editions. Because some instructors avoid assigning problems that are discussed in A Student’s Companion, in the Student Solution Manual or on the Wiley website, while others desire to include a few of these in many assignments, Section Eight of the manual contains a list of these problems. The principal author is grateful to Stanley Williams, who co-authored the first edition of the instructor manual for Fundamentals of Physics. Much of his material has been retained in this manual. He is also grateful to Walter Eppenstein, who helped with suggestions for demonstration and laboratory experiments. Jearl Walker helped significantly by supplying answers to checkpoint questions, end-of-chapter questions, and end-of-chapter problems. The author is indebted to the Project Editor Geraldine Osnato, who managed many aspects of this project. Special thanks go to Sharon Prendergast, the Production Editor. Karen Christman carefully read earlier editions of the manuscript and made many useful suggestions. Her fine work is gratefully noted. The unfailing support of Mary Ellen Christman is joyfully acknowledged. J. Richard Christman Professor Emeritus U.S. Coast Guard Academy New London, Connecticut 06320 Preface iii iv TABLE OF CONTENTS Section One AbouttheText ................ 1 Section Two Suggestions for the Course . ......... 5 Section Three Lecture Notes ................ 11 Section Four Answers to Checkpoints . ........ 164 Section Five Answers to Questions ............ 170 Section Six Answers to Problems ............ 179 Section Seven Comparison of Problems with the Sixth Edition . ........ 233 Section Eight Problems in the Student Solution Manual, in the Student’s Companion, and on the Wiley website . ........ 265 Notes ................... 270 Table of Contents v vi SECTION ONE ABOUT THE TEXT Fundamentals of Physics, seventh edition, follows the sequence of topics found in most intro- ductory courses. In fact, earlier editions of this text were instrumental in establishing that sequence. It is, however, extremely flexible in regard to both the range of topics and the depth of coverage. As a result, it can be used for a two, three, or four term course along traditional lines. It can also be used with many of the innovative courses that are presently being designed and taught. In many instances sections that discuss fundamental principles and give applications are followed by other sections that go deeper into the physics. Some instructors prefer to cover fewer topics than others but treat the topics they do cover in great depth. Others prefer to cover more topics with less depth. Courses of both types can easily be accommodated by selecting appropriate sections of the text. By carefully choosing sections of the text to be included, your course might be a two-term, in-depth study of the fundamentals of classical mechanics and electromagnetism. With the addition of another term you might include more applications and the thermodynamics and optics chapters. In a three-term course, you might also forgo thermodynamics and optics but include Chapter 37 (Relativity) and some of the quantum mechanics chapters added in the extended version. When designing the course, some care must be taken in the selection of topics because many discussions in later chapters presume coverage of prior material. Here are some comments you might find useful in designing your course. Also refer to the Lecture Notes section of this manual. Mechanics. The central concepts of classical mechanics are covered in Chapters 1 through 11. Some minor changes that are possible, chiefly in the nature of postponements, are mentioned in the Lecture Notes. For example, the scalar product can be postponed until the discussion of work in Chapter 7 and the vector product can be postponed until the discussion of torque in Chapter 11. Coverage of Chapter 5 can be shortened to two lectures or elongated to over four, depending on the time spent on applications. Sections 9—8, 9—9, 9—10, and 9—11, on collisions, can be covered as part of laboratory exercises. Other sections in the first twelve chapters that can be used to adjust the length of the course are 2—10, 3—7, 4—8, 4—9, 6—4, 7—8, 9—10, 9—11, 9—12, 11—5, and 11—12. Section 10—7, which deals with the calculation of the rotational inertias of extended bodies, can be covered in detail or can be shortened by simply stating results once the definition as a sum over particles has been discussed. The parallel axis theorem is needed to solve some end-of-chapter problems in this chapter and in Chapter 16 and it should be covered if those problems are assigned. The order of the chapters should be retained. For example, difficulties arise if you precede dynamics with statics as is sometimes done in other texts. To do so, you would need to discuss torque, introduced in Chapter 10, and explain its relation to angular acceleration. This involves considerable effort and is of questionable value. Chapters 12 through 18 apply the fundamental principles of the first 11 chapters to special systems and, in many cases, lay the groundwork for what is to come. Many courses omit one or more of Chapters 12 (Equilibrium and Elasticity), 13 (Gravitation), 14 (Fluids), and 17 (Waves – II). There is some peril in these omissions, however. Chapter 13, for example, is pedagogically important. The central idea of the chapter is a force law and the discussions of many of its rami- fications show by example how physics works. Since the chapter brings together many previously discussed ideas it can be used as a review. In addition, Newton’s law of gravity is used later to introduce Coulomb’s law and the proof that the electrostatic force is conservative relies on the analogy. The basis of Gauss’ law is laid in Chapter 13 and inclusion of this chapter makes teaching About the Text 1 of the law easier. The idea of a velocity field is first discussed in Chapter 14 and is used to introduce electric flux in Chapter 23 (Gauss’ Law). The concepts of pressure and density are explained in Chapter 14 and are used again in the thermodynamics chapters. If Chapter 14 is omitted, you should be prepared to make up for the loss of material by presenting definitions and discussions of velocity fields, pressure, and density when they are first used in your course. Chapter 12 (Equilibrium and Elasticity) can be safely omitted. If it is, a brief description of the equilibrium conditions might be included in the discussion of Chapter 10 or 11. The few problems in later chapters that depend on material in this chapter can be passed over. If Chapter 12 is included, be sure you have already covered torque and have explained its relation to angular acceleration. Chapters 15 (Oscillations) and 16 (Waves – I) are important parts of an introductory course and should be covered except when time constraints are severe. Chapter 15 is required for Chap- ter 16 and both are required for Chapter 17 (Waves – II). Chapter 15 is also required for Chapter 31 (Electromagnetic Oscillations and Alternating Current) and parts of Chapter 16 are required for Chapters 33 (Electromagnetic Waves), 35 (Interference), 36 (Diffraction), 38 (Photons and Matter Waves), and 39 (More About Matter Waves). Chapters 15 and 16 may be covered in the mechanics part of the course or may be delayed until electromagnetic waves are covered. Sections of Chapters 12 through 17 that can be used to adjust the length of the course are 12—6, 12—7, 13—7, 13—8, 13—9, 14—5, 15—6, 15—7, 15—8, 15—9, 16—8, 17—7, 17—9, and 17—10. Thermodynamics. Chapters 18 through 20 cover the ideas of thermodynamics. Most two-term courses and some three-term courses omit these chapters entirely. If they are covered, they can be placed as a unit almost anywhere after the mechanics chapters. The idea of temperature is used in Chapter 26 (Current and Resistance) and in some of the modern physics chapters, as well as in the other thermodynamics chapters. If Chapter 18 is not covered prior to Chapter 26, you should plan to discuss the idea of temperature in connection with that chapter or else omit the section that deals with the temperature dependence of the resistivity. Sections of these chapters that can be used to adjust the length of the course are 18—6, 18—12, 19—6, 19—10, 20—5, 20—6, 20—7, and 20—8.