Table Of Content

S ince defining this course 30 years ago, Paul Hewitt's best-selling text continues as the bench- mark by which all others are judged. In Conceptual Physics with MasteringPhysics®, Twelfth Edition, Paul Hewitt integrates a compelling text and the A Conceptual Approach most advanced media to make physics interesting, understandable, and relevant for non-science majors. to Physics—Now with The Twelfth Edition will delight students with infor- mative and fun Hewitt-Drew-It screencasts, updated content, applications, and new learning activities in MasteringPhysics ! ® MasteringPhysics. 449900 pPAaRrTt ssiixx LLiigghhtt ddiiffffeerreenntt wwaavveelleennggtthhss——wwaavveess ooff llooww ffrreeqquueenncciieess hhaavvee lloonngg wwaavveelleennggtthhss,, aanndd wwaavveess NEW! A new interior design ▶ RReedd ooff hhiigghh ff rreeqquueenncciieess hhaavvee sshhoorrtt wwaavveelleennggtthhss.. 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SSoo,, friendly. tthhee hhiigghheerr tthhee ffrreeqquueennccyy ooff tthhee vviibbrraattiinngg cchhaarrggee,, tthhee sshhoorrtteerr tthhee wwaavveelleennggtthh ooff rraaddiiaanntt FFiigguurree 2266..55 eenneerrggyy..33 IINNTTEERRAACCTTIIVVEE FFIIGGUURREE WWee tteenndd ttoo tthhiinnkk ooff ssppaaccee aass eemmppttyy,, bbuutt oonnllyy bbeeccaauussee wwee ccaannnnoott sseeee tthhee mmoonn- RReellaattiivvee wwaavveelleennggtthhss ooff rreedd,, ggrreeeenn,, ttaaggeess ooff eelleeccttrroommaaggnneettiicc wwaavveess tthhaatt ppeerrmmeeaattee eevveerryy ppaarrtt ooff oouurr ssuurrrroouunnddiinnggss.. WWee aanndd vviioolleett lliigghhtt.. VViioolleett lliigghhtt hhaass sseeee ssoommee ooff tthheessee wwaavveess,, ooff ccoouurrssee,, aass lliigghhtt.. TThheessee wwaavveess ccoonnssttiittuuttee oonnllyy aa mmiiccrroo- nneeaarrllyy ttwwiiccee tthhee ffrreeqquueennccyy ooff rreedd lliigghhtt aanndd hhaallff tthhee wwaavveelleennggtthh.. ppoorrttiioonn ooff tthhee eelleeccttrroommaaggnneettiicc ssppeeccttrruumm.. WWee aarree uunnccoonnsscciioouuss ooff rraaddiioo aanndd cceellll- pphhoonnee wwaavveess,, wwhhiicchh eenngguullff uuss eevveerryy mmoommeenntt.. FFrreeee eelleeccttrroonnss iinn eevveerryy ppiieeccee ooff mmeettaall oonn EEaarrtthh’’ss ssuurrffaaccee ccoonnttiinnuuoouussllyy ddaannccee ttoo tthhee rrhhyytthhmmss ooff tthheessee wwaavveess.. TThheeyy jjiiggggllee iinn uunniissoonn wwiitthh tthhee eelleeccttrroonnss bbeeiinngg ddrriivveenn uupp aanndd ddoowwnn aalloonngg tthheeiirr ttrraannssmmiittttiinngg aanntteennnnaaee.. AA rraaddiioo oorr tteelleevviissiioonn rreecceeiivveerr iiss ssiimmppllyy aa ddeevviiccee tthhaatt ssoorrttss aanndd aammpplliiffiieess tthheessee ttiinnyy ccuurrrreennttss.. TThheerree iiss rraaddiiaattiioonn eevveerryywwhheerree.. OOuurr ffiirrsstt iimmpprreessssiioonn ooff tthhee uunniivveerrssee iiss oonnee ooff mmaatttteerr aanndd vvooiidd,, bbuutt aaccttuuaallllyy tthhee uunniivveerrssee iiss aa ddeennssee sseeaa ooff rraaddiiaattiioonn ooccccuuppiieedd oonnllyy ooccccaassiioonnaallllyy bbyy ssppeecckkss ooff mmaatttteerr.. NEW! Over 200 QR codes ▶ CChheeCCkk PPooiinntt throughout the book allow students to AArree wwee ccoorrrreecctt ttoo ssaayy tthhaatt aa rraaddiioo wwaavvee iiss aa llooww--ffrreeqquueennccyy lliigghhtt wwaavvee?? AAnndd use a mobile device to instantly watch SCreenCASt: speed of Light tthhaatt aa rraaddiioo wwaavvee iiss aallssoo aa ssoouunndd wwaavvee?? Paul Hewitt’s video demonstrations CChheeCCkk YYoouurr AAnnsswweerrss and Hewitt-Drew-It screencasts to YYeess aanndd nnoo.. BBootthh aa rraaddiioo wwaavvee aanndd aa lliigghhtt wwaavvee aarree eelleeccttrroommaaggnneettiicc wwaavveess eemmiitt-- prepare for lecture and gain a better tteedd bbyy vviibbrraattiinngg eelleeccttrroonnss;; rraaddiioo wwaavveess hhaavvee lloowweerr ffrreeqquueenncciieess tthhaann lliigghhtt wwaavveess,, ssoo aa rraaddiioo wwaavvee mmaayy bbee ccoonnssiiddeerreedd ttoo bbee aa llooww--ffrreeqquueennccyy lliigghhtt wwaavvee ((aanndd aa lliigghhtt conceptual understanding of physics. wwaavvee,, ssiimmiillaarrllyy,, mmaayy bbee ccoonnssiiddeerreedd ttoo bbee aa hhiigghh--ffrreeqquueennccyy rraaddiioo wwaavvee)).. BBuutt aa ssoouunndd wwaavvee iiss aa mmeecchhaanniiccaall vviibbrraattiioonn ooff mmaatttteerr aanndd iiss ffuunnddaammeennttaallllyy ddiiffffeerreenntt ffrroomm aann eelleeccttrroommaaggnneettiicc wwaavvee.. ssoo aa rraaddiioo wwaavvee iiss ddeeffiinniitteellyy nnoott aa ssoouunndd wwaavvee.. FFrraaccttaall aanntteennnnaass FFoorr qquuaalliittyy rreecceeppttiioonn ooff eelleeccttrroommaaggnneettiicc wwaavveess,, aa wwhhoollee.. IInn aannyy ffrraaccttaall,, ssiimmiillaarr NEW! Updated applications are ▶ ccoonnvveennttiioonnaall aanntteennnnaa hhaass ttoo bbee aabboouutt oonnee-qquuaarrtteerr sshhaappeess aappppeeaarr aatt aallll lleevveellss ooff available for digital technology, wwaavveelleennggtthh lloonngg.. ThThaatt’’ss wwhhyy,, iinn eeaarrllyy mmoobbiillee ddeevviicceess,, mmaaggnniifificcaattiioonn.. CCoommmmoonn aanntteennnnaass hhaadd ttoo bbee ppuulllleedd oouutt bbeeffoorree tthhee ddeevviiccee wwaass uusseedd.. ffrraaccttaallss iinn nnaattuurree iinncclluuddee environment, and energy. These topics NNaatthhaann CCoohheenn,, aa pprrooffeessssoorr aatt BBoossttoonn UUnniivveerrssiittyy,, wwaass ssnnoowwflflaakkeess,, cclloouuddss,, lliigghhttnniinngg ttrroouubblleedd bbyy aa rruullee iinn BBoossttoonn aatt tthhee ttiimmee tthhaatt pprroohhiibbiitteedd bboollttss,, sshhoorreelliinneess,, aanndd eevveenn are at the forefront of everyone’s tthhee uussee ooff llaarrggee eexxtteerrnnaall aanntteennnnaass oonn bbuuiillddiinnggss.. SSoo hhee ccaauulliiflfloowweerr aanndd bbrrooccccoollii.. consciousness these days and an ffaasshhiioonneedd aa ssmmaallll aanntteennnnaa bbyy ffoollddiinngg aalluummiinnuumm ffooiill iinnttoo ThThee ffrraaccttaall aanntteennnnaa,, lliikkee ootthheerr ffrraaccttaallss,, hhaass aa sshhaappee tthhaatt aa ccoommppaacctt ffrraaccttaall sshhaappee ((aa VVaann KKoocchh fifigguurree——cchheecckk ffrraacc-- rreeppeeaattss iittsseellff.. BBeeccaauussee ooff iittss ffoollddeedd sseellff-ssiimmiillaarr d deessiiggnn,, aa intelligent awareness of their scientific ttaallss oonn tthhee IInntteerrnneett)).. IItt wwoorrkkeedd.. HHee tthheenn eennggiinneeeerreedd aanndd ffrraaccttaall aanntteennnnaa ccaann bbee ccoommpprreesssseedd aanndd fifitt iinnttoo tthhee bbooddyy ppaatteenntteedd mmaannyy pprraaccttiiccaall ffrraaccttaall aanntteennnnaass,, aass ddiidd CCaarrlleess ooff tthhee ddeevviiccee——iitt ccaann aallssoo ssiimmuullttaanneeoouussllyy ooppeerraattee aatt ddiiffffeerr- foundations will give rise to better FPuueennttee,, aann iinnvveennttoorr iinn SSppaaiinn.. BBootthh ffoorrmmeedd ffrraaccttaall-aanntteennnnaa eenntt ffrreeqquueenncciieess.. HHeennccee tthhee ssaammee aanntteennnnaa ccaann bbee uusseedd ffoorr decision making in the political arena. ccoommppaanniieess.. mmoobbiillee-pphhoonnee ccoonnvveerrssaattiioonnss aanndd ffoorr GGPPSS nnaavviiggaattiioonn.. FFrraaccttaallss aarree ffaasscciinnaattiinngg sshhaappeess tthhaatt ccaann bbee sspplliitt iinnttoo ppaarrttss,, HHooww nniiccee tthhaatt tthheessee ddeevviicceess fifitt iinn yyoouurr ppoocckkeett.. CChheeeerrss eeaacchh ooff wwhhiicchh iiss ((oorr aapppprrooxxiimmaatteess)) aa rreedduucceedd ccooppyy ooff tthhee ffoorr ccoommppaacctt ffrraaccttaall aanntteennnnaass!! 33TThhee rreellaattiioonnsshhiipp iiss cc 55 ff ll,, wwhheerree cc iiss tthhee wwaavvee ssppeeeedd ((ccoonnssttaanntt)),, ff iiss tthhee ffrreeqquueennccyy,, aanndd ll iiss tthhee wwaavveelleennggtthh.. MM2266__HHEEWWII99110077__1122__CCHH2266__pppp448855--550033..iinndddd 449900 1100//2214//1133 32::1503 PPMM Outstanding Content T he Mastering system provides tutorials and coaching activities Accompanied by covering content relevant to the conceptual physics course and motivates students to learn outside of class and Unparalleled Tutoring arrive prepared for lecture. Video Activities ▶Video Activities ask students to answer multiple-choice questions based on the content of Paul Hewitt’s popular classroom demonstrations. ▶NEW! More automatically graded Mastering content essay-style end-of-chapter questions have been rewritten as multiple choice. Hint Feedback and hints coach students back onto the right track, emulating how an instructor works with students during an Feedback office-hour visit Interactive Figure Activities Interactive Figure Activities ▶ help students master important topics by interacting with key figures, bringing principles to life. Hints and specific wrong answer feedback help guide students toward understanding the scientific principles. S urvey data show that the immediate feedback and tutorial assistance in MasteringPhysics motivate students to do more home- www.masteringphysics.com work. The result is that students learn more and improve their test scores. Tutorials ▶Assignable, in-depth tutorials guide students through the toughest topics with individualized coaching. These self-paced tutorials coach students with hints and feedback specific to individual misconceptions. Tutorials respond to a wide variety of typical wrong answers that students might enter at any step. Coaching Activity Coaching Activities ▶ have students interact with content, and available hints and/or feedback promote comprehension of the concepts. M asteringPhysics is the leading online homework, tutorial, and assessment product designed to improve results by help- ing students quickly master concepts. Students benefit from self- paced tutorials featuring specific wrong-answer feedback, hints, and a huge variety of educationally effective content to keep them engaged and on track. Robust diagnostics and unrivaled gradebook Student Results reporting allow instructors to pinpoint the weaknesses and misconceptions of a student or class to provide timely intervention. ▶ NEW! Learning Catalytics™ is a “bring your own device” student engagement, assessment, and classroom intelligence system. With Learning Catalytics you can: • Assess students in real time, using open-ended tasks to probe student understanding. • Understand immediately where students are and adjust your lecture accordingly. • Improve your students’ critical-thinking skills. • Access rich analytics to understand student performance. • Add your own questions to make Learning Catalytics fit your course exactly. • Manage student interactions with intelligent grouping and timing. Learning Outcomes A learning objective has been added to ▶ help the students focus on the most important concepts in each chapter. These learning outcomes are associated with content in MasteringPhysics®, allowing the work of tracking student performance against course learning outcomes to be done automatically. Gradebook Diagnostics ▶ The Gradebook Diagnostics screen allows you to quickly and easily identify vulnerable students, difficult problems, and your students’ most common misconceptions. MasteringPhysics. It’s magnetic! It’s electric! It will shock you! CONCEPTUAL This page intentionally left blank CONCEPTUAL Twelfth Edition written and illustrated by Paul G. Hewitt City College of San Francisco Boston Columbus Indianapolis New York San Francisco Upper Saddle River Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montreal Toronto Delhi Mexico City Sao Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo Publisher: Jim Smith Design Manager: Derek Bacchus Project Manager: Chandrika Madhavan Text Design: Tamara Newnam Assistant Editor: Kyle Doctor Cover Designer: Tamara Newnam Marketing Manager: Will Smith Illustrations: Rolin Graphics, Inc. Program Manager: Mary O’Connell Photo Researcher: Stephen Merland, PreMediaGlobal Senior Content Producer: Kate Brayton Image Lead: Maya Melenchuk Production Service and Composition: Cenveo(cid:183) Manufacturing Buyer: Jeffrey Sargent Publisher Services Printer and Binder: Courier/Kendallville Project Manager, Production Service: Cindy Johnson Cover Printer: Lehigh/Phoenix Copyeditor: Carol Reitz Cover Photo Credit: Top Seller/Shutterstock Credits and acknowledgments for materials borrowed from other sources and reproduced, with permission, in this textbook appear on page C-1. Copyright ©2015, 2010, 2006 Paul G. Hewitt, 300 Beach Drive NE, 1103, St. Petersburg, FL 33701. 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. Library of Congress Cataloging-in-Publication Data Hewitt, Paul G., author. Conceptual physics / written and illustrated by Paul G. Hewitt, City College of San Francisco. -- Twelfth edition. pages cm Includes index. ISBN 978-0-321-90910-7 1. Physics--Textbooks. I. Title. QC23.2.H488 2015 530--dc23 2013035027 ISBN 10: 0-321-90910-0; ISBN 13: 978-0-321-90910-7 (Student edition) ISBN 10: 0-321-90979-8; ISBN 13: 978-0-321-90979-4 (Books a la Carte Edition) ISBN 10: 0-133-49849-2; ISBN 13: 978-0-133-49849-3 (NASTA) www.pearsonhighered.com 1 2 3 4 5 6 7 8 9 10—CRK—16 15 14 13 12 To my grandchildren, Manuel, Alexander, Megan, Grace, and Emily and to all students who struggle to learn physics