Physics PDF
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PHYSICAL SCIENCE STUDY COMMITTEE PROPERTY ScU ( +< Bentftlem Township {jerry S+a.hl School District for #f.0*/ This book is the Property of m Soi+U Virtue* of 3***4tfe* 7** *Aift CORNWELLS HEIGHTS BUCKS COUNTY • PENNSYLVANIA 00338 Oy rhot.,4 1fl9(r.l Cost w*4*, IIf. 1. Any pupil who loses, or destroys this book will be required to pay itsvalue. 2. Damage to this book will be assessed on the life and cost of the book. 3. Keepthis book covered at all times. 4. Do notwrite in or mark this book in any way. 5. Do not carry paper or pencils in this book. CONDITION NAME SEPT. JUNE ,_£Li9£2 Ge*RY STAWL >£3 //- 3 tiBW HV i£Zy9Qs\ G zrrY Stahl /i-1-i HtW ?_ 19 » 19 9 19 9 19 > 19 9 19 9 19 9 19 ^r - ^a i o 2-1 29 /! ,/-/-< **- ' Z3 -z -2.0- 2.? 2^ * ~ 2 PHYSICS Digitized by the Internet Archive 2012 in http://archive.org/details/physicsOOphys PHYSICS PHYSICAL SCIENCE STUDY COMMITTEE HEATH AND COMPANY, BOSTON D. C. LIBRARY OF CONGRESS CATALOG CARD NUMBER 60-13412 Published by D. C. HEATH AND COMPANY under arrangements with EDUCATIONAL SERVICES INCORPORATED Copyright © 1960 Educational Services Incorporated No part of the material covered by this copyright may be reproduced in any form without written per- mission of thepublisher. Printed in the United States ofAmerica. (6J0) PREFACE The Physical ScienceStudyCommitteeisagroup students was sought. In 1957-58, eight schools and of university and secondary school physics teachers 300studentstriedouttheearlymaterials. Theircom- working to develop an improved beginning physics ments and suggestions helped to improve and extend course. Theprojectstartedin 1956withagrantfrom the content and approach. Then in 1958-59, nearly the National Science Foundation, which has given 300 schools and 12,500 students used the course, and the main financial support. The Ford Foundation in 1959-60, almost 600 schools and 25,000 students and the Alfred P. Sloan Foundation have also con- participated in the third test year. The course was tributed to the support ofthe program. thoroughlyrevised in thelight ofthis experience. Thistextbook istheheartofthe PSSC course, in Thereactions ofteachersand students show that whichphysics is presented notasa mere bodyoffacts a large percentage of students are intrigued by this but basically as a continuing process by which men course and do well with it. Their concepts grow seek to understand the nature of the physical world. through exploration in the laboratory, analysis in the Besides the textbook there are the following closely text, and study of the films. The course appeals to correlated parts: a laboratory guideanda setofnew students who are inclined toward the humanities as and inexpensive apparatus; a large number offilms; well as to thosewho arealready interested in science. standardized tests; a growing series of paper-back books by leaders in related fields; andacomprehen- sive teacher's resource book directly related to the The PSSC Course course. The PSSC course consists of four closely inter- The PSSC physics course is the work of several connected parts. Part I is a general introduction to hundred people, mainly school and college physics the fundamental physical notions oftime, space, and teachers, over a period of four years. A brief ac- matter: how we grasp and how we measure them. count of this collaboration is given attheend ofthe As the student learns of the almost boundless range book. Here it is appropriate, however, to recognize ofdimensions from the immensely large to the infini- two of these collaborators. Professor Jerrold R. tesimallysmall,frommicrosecondstobillionsofyears, Zacharias, the Department of Physics of the Massa- he finds out how these magnitudes can be measured. chusetts Institute of Technology, called together a He learns that instruments serve as an extension of committeeofleadersinphysicsandineducation from hissenses. Laboratoryexperienceshowshowwefirst which this project sprang. He has been active in all measurebydirectcountingandthenextendourrange phasesoftheproject. ProfessorFrancisL. Friedman, of measurements by calibrating and using simple in- also of the Department of Physics at MIT and a struments such as stroboscopes orrange finders. member of the Committee from the beginning, has From these experiments measuring time and played the major role in developing the textbook space, the student moves to an understanding of ve- and has contributed significantly to all parts of the locityandacceleration, ofvectors and ofrelative mo- program. tion. Hethen goes on to study matter, which we see In many ways this new course differs markedly movingthroughspacein the course oftime. In this from the beginning physics course usually taught in first examination of matter, we develop the concepts the United States. To besurethatthe newapproach of mass and of its conservation. We then use the was sound and teachable, the help of teachers and evidenceofphysicistsandchemiststofindthatmatter VI PREFACE is made ofrelatively few kinds ofatoms. Direct ex- The laws of conservation of momentum and of perience is provided in the laboratory. There, for energy are introduced through a combination of instance, the students compute the size ofa molecule theory and laboratory exploration. These laws form from measurements ofthin films ofoil. Moving pic- a substantial portion of Part III, and we stress their tures extend this direct laboratory experience by use in situations where detailed observation of the showing experiments which are beyond the reach of motion is not possible, as in Chadwick's discovery of students. the neutron and in the kinetic theory ofgases. Throughout, the student is led to realize that Part IV introduces the student to electricity and physics is a single subject of study. In particular, through it to the physics ofthe atom. Here the stu- time,space,andmattercannotbeseparated. Further- dent uses the knowledge of dynamics gained in Part more, heseesthat physicsisadevelopingsubject, and III. We begin with qualitative observations, then that this development is the imaginative work ofmen proceed to a quantitative study ofthe forces between and women like him. charges. We learn how to measure very small elec- The topics in the PSSC course are selected and tric forces and discover that electric charge comes in ordered to progress from the simple and familiar to natural units. We then study the motion ofcharged the more subtle ideas ofmodern atomic physics. In particles in electric fields and learn how to determine Part I we have looked at a broad picture ofthe uni- the masses ofelectrons and protons. verse. Now as we examine certain fields of physics Next comes a discussion of magnetic fields pro- in more detail, we startin Part II with light. We live duced by magnets and currents, and a discussion of by light, and the student moves easily into a study of the forces they exert on moving charges. As a final sharp and diffuse shadows, reflection in mirrors, and part of electricity we discuss the induction laws and the refraction of light at optical boundaries. The give the student a qualitative feeling for the electro- natural development of the subject leads us to de- magnetic nature of light. Many of the—fundamental velop a particle theory (or model) of light. Its dis- ideas are explored in the laboratory Coulomb's cussion illustrates repeatedly the manner in which Law, the magnetic field around a current, the force virtua—lly all scientific knowledge develops. Again exerted bya magneticfield on a current-carryingwire f—ilms for instance, the film on the pressure oflight are examples. help the student to go beyond thelaboratory. Now we use the knowledge gained on a large Under continued scrutiny the particle model scale to probe the structure ofatoms. Followingthe provesinadequate, andthestudentfindsthatweneed work of Rutherford, we establish the nuclear model — another model a wave model. The laboratory of the atom. But some questions are unanswered. againprovidesanunexcelledsourceofexperience,and Why, for example, is such an atom stable? Why here the student becomes familiar with the properties doesn'titcollapsebyemittinglight? Insearchingfor ofwaves. Heobservesthebehaviorofwavesonropes answers, we discover that light is both grainy and and on the surface ofwater. He begins to recognize wavy. Furthermore, we find that although matter the group of characteristics that constitute wave be- behaveslikeparticles, insomerespectsitalsobehaves havior. Knowledge of interference and diffraction like waves. By combining both properties, we can comesdirectlyfrom astudy ofwaves in arippletank. understandthestabilityofthehydrogenatomandthe Forthefirsttime, perhaps, thesmearsoflightaround structure of its energy levels. In this part of the streetlamps,thecolorsofoilslicks,andtheformation course, because direct experimentation becomes of images by lenses appear as aspects of the wave harder and more expensive, films bring to the stu- nature oflight. dentsuchexperimentsas the Millikanexperimentand During the first halfof the course, the principal theinterferenceofphotons. Attheendofthecourse emphasis is on the kinematics of our world: where wehavearrived at the modern model ofatoms. thingsare, how bigtheyare, andhow they move, not The PSSC course as now presented has proved why. In Part III we turn to a closer look at motion, to be thoroughly teachable. It is useful in a wide this time from a dynamical point of view. With variety of schools. However, those who have col- simple laboratory apparatus the students discover laborated in building this course wish to improve it Newton's law ofmotion. They learn to predict mo- further. As the Physical Science Study Committee tions when forces are known and to determineforces continues this development, your comments will al- when motions are known. Thus armed they follow ways be welcome. the extraordinary story of the discovery ofuniversal gravitation, Newton's educated guess with which he James R. Ktllian, Jr. jumpedfrom theknownlaws ofmotionto thelaw of Chairman, Board ofTrustees gravitational attraction. Educational Services Incorporated
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