Physics

776 Pages·1979·39.534 MB·English

by  Jay Orear

Some
ephySical Constants
See Appendix A for a more complete list with four-place accuracy.
x
Speed of light c 3.00 108m/s
Acceleration due to gravity g 9.8 m/s2
Gravitational constant G 6.61 X 10-11 N m2/kg2
&30
Boltzmann’s constant k 1.38 X 10-23 J/K
Avogadro’s number 6.02 X 1023/mole
K
Elementary charge e 1.60 X 10“19C
Electron mass me 9.1 X 10-31 kg
Proton mass mp 1.67 x 10-27 kg
Planck’s constant h 6.63 X 10-34 J s
Mass of earth K 5.98 X 1024 kg
Mass of moon 7.36 X 1022kg
Mm
Mass of sun 1.99 X 1030 kg
K
Earth-moon distance 3.80 X 105 km
Radius of earth 6.35 X 103 km
K
Electrical constants: k0 = 1/(4t7€0) 9.00 X 10® N m2/C2
k0/c2 = Ho/>4,7 10-7 N s2/C2
8.85 X 10”12 F/m

ephysicS
From the front to rear cover is a span of almost 4000 years in the prog¬
ress of science. Stonehenge on the front cover was built in 1900 B.c. by
the scientists of that period in England. Fermilab on the rear cover was
built in A.D. 1970 by scientists in the United States; a view of the central
laboratory building is shown. [Stonehenge photo by Preston Lyon; Fermi¬
lab photo by Photography Department, Fermi National Accelerator Lab¬
oratory. ]
Enrico Fermi, 1901-1954
Jay OreaiT
'
CORNELL UNIVERSITY
Macmillan Publishing Co., Inc.
NEW YORK
Collier Macmillan Publishers
LONDON
Copyright © 1979, Jay Orear
Printed in the United States of America
All rights reserved. No part of this book may be reproduced or transmitted in any form or
by any means, electronic or mechanical, including photocopying, recording, or any infor¬
mation storage and retrieval system, without permission in writing from the Publisher.
Macmillan Publishing Co., Inc.
866 Third Avenue, New York, New York 10022
Collier Macmillan Canada, Ltd.
Library of Congress Cataloging in Publication Data
Orear, Jay.
Physics.
Includes index.
1. Physics. I. Title.
QC21.2.073 530 77-28180
ISBN 0-02-389460-1
Printing: 1 2 3 4 5 6 7 8 Year: 9 0 1 2 3 4 5
This book is intended as a text for a one-year or a one-and-a-half-year
introductory physics course for science and engineering students. Prior
knowledge of calculus is not needed, but a course based on this book
'Should be concurrent with a calculus course. The mathematical and
conceptual level of this book is not intended to exceed that of currently
popular texts. However, this book differs from most others in two respects:
1 There is a unified presentation of up-to-date physics.
2 Whenever possible, “laws” of physics are derived from the basic
principles; that is, the distinction between the basic principles and what
is derivable from them is emphasized.
The relationships among the different fields of physics (as well as
science and technology) are made clear. Seemingly independent topics are
unified and tied together into one grand overview. When a new “law” of
physics, such as magnetic force on a moving charge or equipartition of
energy, is introduced, I try to make clear whether it is truly a new
fundamental law or can be derived from preceding material. In most cases
there are simple derivations that help delineate the logical structure and
beautiful unity of what might otherwise seem to be an encyclopedic listing
of diverse phenomena and laws. Such so-called laws as Ampere’s law,
Faraday’s law, the equipartition of energy, magnetic force, Ohm’s law,
slower speed of light in matter, Hooke’s law, and Huygens’ principle are
derived from the more fundamental laws where possible. They are not
presented as new, independent laws of physics. I feel obligated to explain
the reason “why” whenever possible. If a derivation is too difficult, the
reader is at least told that a derivation is possible and plausibility argu¬
ments are given. These “secondary laws” make possible further experi¬
mental predictions upon which the survival of the basic laws depends.
If all of electromagnetism is to be “derived” from Coulomb’s law, a
V
prior understanding of special relativity is helpful. For this reason rela¬
tivity is presented in Chapters 8 and 9, before electromagnetism (Chapters
15-21). Nevertheless, the chapters on electromagnetism are written in such
a way that those wishing to do so may skip Chapters 8 and 9. If relativity
is to be deferred, it should not be deferred past Chapter 24.
Since a true understanding of the structure of matter and many other
physical phenomena rests upon quantum theory, the basic principles of
quantum theory are presented in Chapters 24 and 25. Understanding of
the quantum theory is strengthened in the chapters that follow by quan¬
titative applications in atomic physics, solid-state physics, nuclear physics,
astrophysics, and particle physics. With this background in quantum
mechanics and relativity, it is even possible to make simple calculations of
the radius and constituents of neutron stars and black holes (Chapter 30).
Some may worry that such “advanced” topics as neutron stars, black
holes, Fermi energy, conservation of parity, quarks, holography, time
dilation, and intensity interferometry are too difficult for beginning
students. I include them because these new developments capture the
imagination of students as they read of them in newspapers and maga¬
zines. Students come to college expecting to learn more about such
exciting things in their physics course. My classroom experience shows that
many of these so-called advanced topics are easier for students to grasp
than the implications of Newton’s third law.
Another legitimate concern is whether students planning to become
engineers should be exposed to these modern ideas. I find that few
professors of engineering want the introductory course to be an applied
physics course or an engineering course. The introductory physics course
for engineering majors may be the students’ only chance to see how the
different fields tie together. It may be their only chance to learn of new
developments and how these relate to other fields of science and technol¬
ogy. Thus there is some effort to relate the study of physics to other fields
of science and give attention to the impact of science on society. For
example, the world shortage of energy is a central theme that runs
throughout the book. Other social, political, economic, and philosophical
implications of science are discussed. Not only does this physics course lay
the theoretical foundations for a future profession, but it should also
contribute to the cultural background expected of a person who will be
involved with science and technology. And, as previously implied, an
understanding of relativity and quantum mechanics is necessary for
proper understanding of most natural phenomena.
Many examples are given, with emphasis upon those of social signifi¬
cance. Although some examples are used to illustrate interesting side
applications, most provide instruction in problem-solving technique.
Those examples that might be too difficult for a beginning student are
labeled with a star. In addition to the worked-out examples distributed
throughout the text, there are many problems at the ends of chapters.