Fundamentals of Physics

544 Pages·1975·47.817 MB·English

by  B. M. Yavorsky,  A. A. Pinsky

explains the con­
This texlbook
cepts and advances
111osL important
modern physics without resort
of
to igh r rnatli!'lmatics. Avoids the
h e
Lraditio11al division between clas­
sical and modern physics and en­
deavours to present all material so
to develop quantum mechanical
as
concepts.
The tex lbook is i1 1tended for secon­
dary schools and as a teaching aid for
physics Leachers in general and
tech11ical secondary schools. Will
be 1'011 nd useful by correspondence
stndents studying level and
•A'
year physics,
first
I I. Vibrations and
Contents. Vol.
Waves. Quantum Physics of Atoms,
Molecules and Solids. Physics of
the Nucleus and Elementary Par­
ticles.
Prof. VOHSK l>ocLor
BOH IS YA Y,
of Physical and Mnl.hornaticuJ Sci­
ences, ii; dupurl.111u11t of
in thu
theoret.icul phy1-1ic1-1 ut the Louin
State Pedag-ogicui nstit11 te i 11
I Mm1-
cow. le boe11 lect11ri11g i 11 higher
I has
ed11catio1111l irn.;Lit11tio111-1 of the
So­
viet tho last years.
Union Jor �fi
Prof. Yavorsky has written about
publishecl works: hooki; and ar­
:mo
ticles in v ario11s scion ti tic o11rn als
j
1111d collected papers, thorn
anwng the·
in three
Complete Course in Physics (
volumes anct' some other text-·
)
books and aicls for institute tea­
chers.
Assoc. Prof. AH KADY PINS Y,
K
Candidate of Pedagogical Sciences,
is a senior :;cicntist at the Scientifie
Research Institute for Teaching
Practice of the Academy of
USSH
Pedagogical Sciences. lie has spe­
cialized in the methods of physics
teaching at school and university
levels. In this field he has published
over 50 works, including several
books·. on methods of teaching
physics.
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B. M. YAVORSKY and A. A. PINSKY
FUNDAMENTALS of PHYSICS
VOLUME
I
MOTION AND FORCES.
CONSERVATION LAWS.
MOLECULAR-KINETIC THEORY OF GASES.
MOLECULAR FORCES AND STATES
OF AGGREGATION OF MATTER.
ELECTRODYNAMICS.
Translated from the Russian
by
NICHOLAS WEINSTEIN
MOSCOW
MIR PIIBLISHEBS
First published 1975
from t 1974 Russian edition
Revised he
Ha anz11uuc1w.M. J!JbllU
1974
© lfal{aTeJibCTBO «HayKa»,
© English translation, Mir Publishers, 1975
CONTENTS
FOREWORD 15
Part one
MOTION AND FORCES
Chapter 1 VELOCITY . . . . . . . 19
1.1. Mechanical motion 19
1.2. Frames of reference. Paths . . 20
1.3. Rectilinear motion. Motion equations 22
1.4. Uniform motion . . . . . . . . . . 23
1.5. Variable motion . . . . . . . . . . . 24
1.6. Average velocity . . . . . . . . . . . . 25
1.7 . Instantaneous velocity of variable motion
27
Chapter 2 INERTIA . . . . . . . 28
2.1. The principle of inertia 28
2.2. Inertial reference frames 30
2.3. The principle of relativity 32
2.4. Galilean transformations . . . . . . 33
2.5. Classical law of the addition of velocities 35
Chapter 3 SCALARS AND VECTORS. VELOCITY VECTOR 35
3.1. Scalar quantities . . . . . . . . . . 35
3.2. Vector quantities . . . . . . . . . . 36
3.3. Certain operations on vectors . . . . . 37
3.4. Resolving a vector into two components 39
3.5. Velocity is a vector 40
3.6. Addition of velocities 42
Chapter 4 ACCELERATION 43
4.1. Average and instantaneous acceleration 43
4.2. Rectilinear variable motion . . . .
4.3. Uniformly accelerated rectilinear motio.n . . 4444
4.4. Velocity graph for uniformly accelerated motion 45
4.5. Graphical calculation of displacement . . . . . . . . . 45
4.6. Displacement and average velocity in uniformly accelera-
ted motion . . 46
4.7. Uniform circula· r. m.ot.io.n o.f .a p.ar.ti.cle. .. .. .. .. .. .. .. .. .. . 48
4.8. Acceleration in uniform circular motion of a particle . . . 48
6 CONTENTS
Chapter FORCE . . . . . . . . . . . . . . . 50
5
5.1. Force, a measure of the interaction of bodies 50
5.2. Elastic and plastic deformation . . . . . 51
5.3. Force is a vector . . . . . . . . . . . . . . . . . . 52
5.4. Vector addition and resolution of forces applied to a particle 54
Chapter WEIGHT AND MASS 55
6
6.1. Force of gravity. Weight . 55
6.2. Free fall . . . . . . . 57
6.3. Mass of a body . . . . . 58
6.4. The density of substances 59
Chapter FUNDAMENTAL LAW OF DYNAMICS 60
7
7 .1. Force and acceleration . . . . . . . . . 60
7.2. Applying the fundamental law of dynamics 63
7.3. Weightlessness .
7 .4. System of units . .. .. .. .. .. .. .. .. .. .. 6607
7.5. The international system of units 68
7.6. The cgs and mk(force)s systems of units 69
Chapter 8 EQUATIONS OF MOTION AND INITIAL CONDITIONS 69
8.1. The basic problem of dynamics . . . . . . . . . . . . 69
8.2. Motion of a particle subject to the force of gravity . . . . 70
8.3. Numerical solution of the basic problem of dynamics 72
8.4. Motion of a body subject to an elastic force . . . . . . . 73
8.5. Quantities determining the motion equation of a particle 77
Chapter 9 GRAVITATION 78
9.1. Discovery of the law of gravitation . . 78
9.2. Newton's law of universal gravitation 80
9.3. The Cavendish experiment . . . . . . . . . . . . 81
9.4. Determining the distances from the 'sun to the planets 82
9.5. The gravitational field . . . . . . . . . . . . 83
9.6. Gravitational· field intensity . . . . . . . . . . 84
9.7. The earth's gravitational field . . . . . . . . . . 84
9.8. Effect of the earth's rotation of free-fall acceleration 86
Chapter ELECTRIC FORCES . . 87
10 . . . • .
10.1. Electric charge . . . . . . . . . 87
10.2. Coulomb's law . . . . . . . . . 88
10.3. Units of charge and systems of units 90
10.4. The electric dipole . . . . . . . 92
10.5. The electric field. Field strength . . . . . . 94
10.6. Electric field of point charge and of a dipole 94
a
Chapter FRICTION 97
11
11.1. External and internal friction 97
11.2. Static friction . . . . . 97
11.3. The angle of friction . . . . 100
11.4. Sliding friction . . . . . . 101
11.5. Rolling friction . . . . . . 102
11.6. Motion of bodies sub.j ec. t .t o . th. e .f or. c·e. of friction 102
11.7. Internal friction 103
11.8. Motion of bodies in fluids 105
11.9. Bodies falling in a fluid 108
CONTENTS 7
Chapter 12 THE THEORY OF RELATIVITY 110
12.1. Velocity of light and the law of addition of velocities 110
12.2. Basic postulates of the special theory of relativity . 113
12.3. Simultaneity of events . . . . . . . . . 113
12.4. Simultaneity and length . . . . . . . . 116
12.5. Relativistic law for the addition of velocities 116
12.6. Limiting nature of the velocity of light 118
12. 7. Lorentz transformations . . . . . . . . 119
12.8. Length or distance . . . . . . . . . 120
12.9. Time interval between two events . . . .. 121
12.10. The time interval between cause and effect . . . . . . . 122
12.11. The relation between relativistic and Newtonian mechanics 123
<-:hapter MASS, MOMENTUM AND FORCE IN THE THEORY OF
13 RELATIVITY . . . . . . . . . . . . . . . . . . . . . 125
13.1. Relativistic mass . . . . . . . . . . . . . . . . . . 125
13.2. The fundamental law of dynamics in the theory of relativity 126
13.3. The relation between Newtonian and relativistic dynamics 128
Chapter 14 EQUATIONS OF MOTION AND THE UNCERTAINTY
RELATION . . . . . . . . . . . . . . , . . . 130
.
14.1. Initial conditions and measuring apparatus . . . 130
14.2. The uncertainty relation . . . . . . . . . . . 134
14.3. The uncertainty relation and classical mechanics 134
Part
two
CONSERVATION LAWS
Chapter LAW OF CONSERVATION OF LINEAR MOMENTUM 138
15
15.1. Closed system of bodies . . . . . . . 138
15.2. Law of conservation of linear momentum 139
15.3. Recoil phenomena . . . . . . . . . 141
15.4. Measurement of mass . . . . . . . . 142
15.5. Jet propulsion (propulsion by reaction) 143
15.6. Rocket fuel calculations . . 144
15. 7. Centre of mass . . . . . . . . . 145
15.8. Motion of the centre of mass 146
Chapter TOTAL AND KINETIC ENERGY 148
16
16.1. Total energy of a body . . . . 148
16.2. Kinetic energy . . . . . . . 149
16.3. Energy and linear momentum 150
16.4. Kinetic energy and work 151
16.5. Power . . . . . . . . . . . 153
16.6. Units of energy, work and power . . . . . 154
16. 7. Momentum, and energy of localized particle 155
a
Chapter ELEMENTARY COLLISION THEORY 157
17
17.1. What is a collision? . . . . . . . . . 157
17 .2. Completely inelastic collision . . . . 158
17. 3. Elastic collision . . . . . . . . . . 160
17.4. Neutron moderation . . . . . . . . . . 162
17. 5. Pressure of a stream of particles on a wall 163
Chapter 18 CONSERVATIVE FORCES AND POTENTIAL ENERGY 165
18.1. Work done by a variable force . . . . . . . . . . . . 165
18.2. Work done by an elastic force . . . . . . . . . . . . . 167
8 CONTENTS
18.3. Work done by a Coulomb force . . . . . . . . . . . . 168
18.4. Work done by a gravitational force . . . . . . . . . 170
18.5. Conservative forces . . . . .. . . . . . . . . 171
18.6. Potential energy of elastic, Coulomb and gravitational inte-
ractions . . . . . . . . . . . . . . . . . . . 172
18. 7. Potential of an . electrostatic field . . .. . . .. . . . 174
18.8. Electric potential of the field set up by a point char, ge 175
18.9. Energy of an electric field . . . . . . 176
. . . . . . •
Chapter LAWOFCONSERVATIONOFENERGY INNEWTONIAN
19
MECHANICS . . . . . . . . . . . 177
.
19.1. Mechanical energy and its conservation 177
19.2. Mechanical energy and friction 177
19.3. Space velocities . . . . . . . . . 178
19.4. Looping the loop . . . . . . . . 179
19.5. Potential energy curves . . . . . . 180
19.6. Potential energy and equilibrium 183
Chapter INTERNAL ENERGY .
20 . . . . . 184
20.1. Internal energy of a system of particles . . . . . 184
.
20.2. Changes in internal energy when a body is deformed . . . 85
20.3. Changes in internal energy of a body in thermal processes 1186
20.4. Changes in internal energy in chemical reactions 187
20.5. Changes in internal energy in nuclear reactions 188
Chapter THE LAW OF CONSERVATION OF ENERGY 189
21
21.1. Work as a measure of the change in total and internal energy 189
21.2. Heat exchange . . . . . . . . 190
21.3. Quantity of heat . . . . . . . . 192
21.4. The first law of thermodynamics 193
21.5. An adiabatically isolated system 194
21.6. The law of conservation of energy 194
21. 7. The law of conservation of mass 195
21.8. More about relativistic mass 197
Chapter 22 THE LAW OF CONSERVATION OF ANGULAR MOMEN-
TU:l\<I . . . . . . . . . . . . . . . . . 199
22.1. Features rotational motion . . . . . . . . . . 199
22.2. Kinetic eonfe rgy and moment of ine. rt.i a• . . . . . . 199
22.3. Dependence of the moment of inertia on the l. ocation of the
axis of rotation . . . . . . . . . . . . . . . . . . . 201
22.4. Moment of force . . . . . . . . . . . . . . . . . . . 204
22.5. Equilibrium conditions for a body having an axis of rotation 205
22.6. Angular momentum and the fundamental law of dynamics 205
22. 7. The law of conservation of angular momentum . . . . . 207
22.8. Analogies between quantities and their relations in transla-
tional and rotational motion . . . . . . . . . . . . . 209
Chapter SYMMETRY IN NATURE AND THE CONSERVATION
23
LAWS . . . . . . . . . . . . . . . . . . . . 211
23.1. The conservation laws are nature's principal laws 211
23.2. The conservation laws are forbiddenness principles 212
23.3. The conservation laws and space-time symmetry . 2 3
23.4. Uniformity of time and the conservation of energy . 2114
CONTENTS
Chapter NONINERTIAL FRAMES OF REFERENCE AND GRA-
24
VITATION 214
• • • • • . . . . • . . . . .
24.1. Phenomena in an accelerated reference frame 214
24.2. Inertial forces . . . . . . . . . . . . . . 216
24.3. Features of inertial forces . . . . . . . . 218.
24.4. Space and time in noninertial reference frames 219
24.5. The principle of equivalence . . . . . . . 222
24.6. An idea of Einstein's theory of gravity 224
, 24. 7. The twin para ox 228.
?
Part three
MOLECULAR-KINETIC THEORY OF GASES
Chapter MOLECULAR MOTION . . 231
25 • • • .
25.1. How molecular speeds were measured 231
25.2. Molecular speed distribution 233
25.3. Mean free path of molecules 235
25.4. Diffusion . . . . . . . 238-
25.5. Law of diffusion 239
25.6. Separation of gas mixtures 240
Chapter 26 AN IDEAL GAS 242
26.1. Gas pressure 242
26.2. Units of pressure 244
26.3. An ideal gas 246
26.4. Temperature . . . . . . . . . . . . . . . . . . . . 248.
26.5. Absolute temperature and the equation of state of an ideal
gas . . . . . . . . . . . . . . . . . . . . . . . 249-
26.6. The constant-volume gas thermometer . . . . . . . . 250
26. 7. The degree and the kelvin. The practical and absolute tem-
perature scales . . . . . . . . . . . . . . 251
26.8. Absolute zero . . . . . . . . . . . . . . 253
26.9. Avogadro's number .and Boltzmann's constant 254
26.10. Molecule distribution in a force field . . . . . 256
26.11. Barometric distribution . . . . . . . . . 258.
Chapter AN IDEAL GAS AND THE FIRST LAW OF THERMODY-
27
NAMICS . . . . . . . . . . . . . . . . . . . . 260
.
27.1. Internal energy of a monatomic ideal gas . . . . . . . . 260
27.2. Work done in the expansion of an ideal gas . . . . . . . 261
27.3. The first law of thermodynamics and the specific heat of a gas 262
27.4. Isochoric processes 264
27.5. Isobaric processes 265
27.6. Isothermal processes 266
27.7. Adiabatic processes 267
27.8. Specific heat of a diatomic gas . . . . . . 26!}
27.9. Quantum theory of the specific heats of gases 272
Chapter 28 THE SECONJ? LAW OF THERMODYNAMICS 276
28.1. Quasi-static processes . . . . . . . . 276
28.2. Reversible processes . . . . . . . . . 277
28.3. Irreversibility of real thermal processes 278.
28.4. Irreversibility and statistics . . . . . . 27!}
28.5. Diffusion and thermodynamic probability 282