PHYSICS CURIOSITIES, ODDITIES, AND NOVELTIES JOHN KIMBALL PHYSICS CURIOSITIES, ODDITIES, AND NOVELTIES PHYSICS CURIOSITIES, ODDITIES, AND NOVELTIES JOHN KIMBALL CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2015 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20150209 International Standard Book Number-13: 978-1-4665-7636-0 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. 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Contents P REFACE xv A BOUT THE AUTHOR xvii C HAPTER 1 N EWTON AND M ECHANICS 1 1.1 Introduction 1 1.2 Newton’s Equation 1 1.2.1 Data for Newton: Falling 2 1.2.2 Newton’s Tools: Mathematics 3 1.2.3 Newton’s Equation 4 1.2.4 Newton’s Laws 4 1.2.5 Mass m 5 1.2.6 Acceleration a and Acceleration of Gravity g 6 1.2.7 Ballistics 7 1.2.8 Lift and Drag 8 1.2.9 Gravity and Acceleration 9 1.2.10 Acceleration Examples 10 1.2.11 Force F 11 1.2.12 Fast Cars and Animals 12 1.2.13 Acceleration without Speed Change: Curved Paths 13 1.3 Gravity 15 1.3.1 Gravitational Field 16 1.3.2 Inverse Square Law 17 1.3.3 Measuring G 18 1.3.4 Mutual Attraction 19 1.3.5 Falling Objects, Earth’s Mass, and Weight Loss 20 VII VIII CONTENTS 1.4 Solar System and Beyond 21 1.4.1 Distance-to-Radius Ratios 22 1.4.2 Distance to the Moon 23 1.4.3 Size of Earth 24 1.4.4 Size of the Sun and Distance to the Sun 25 1.4.5 Kepler’s Laws 26 1.4.6 Applications of Kepler’s hird Law Formula 28 1.4.7 Jupiter Mass 29 1.4.8 Dark Matter 30 1.4.9 Moon Mass 31 1.4.10 Extrasolar Planets 32 1.5 Causality and Chaos 33 1.5.1 Gravity Is Not the Only Force 33 1.5.2 Causality 33 1.5.3 Chaos = Unpredictable 34 C HAPTER 2 M OMENTUM, A NGULAR MOMENTUM, AND E NERGY 39 2.1 Introduction 39 2.2 Momentum 39 2.2.1 Momentum Conservation 40 2.2.2 Examples 40 2.2.3 Drag and Lift 43 2.3 Angular Momentum 47 2.3.1 Torque 47 2.3.2 Angular Momentum Deinition 50 2.3.3 Angular Momentum Conservation 50 2.3.4 Kepler and Angular Momentum 50 2.3.5 Is a Day Really 24 Hours? 52 2.3.6 Astronomy 54 2.3.7 Gyroscopes (and Tops) 56 2.4 Energy 57 2.4.1 Kinetic Energy 58 2.4.2 Potential Energy of Height 59 2.4.3 Energy Conservation Examples 59 2.4.4 Work and Power 60 2.4.5 Athletic Achievements 63 2.4.6 he Pendulum, Harmonic Oscillators, and Resonance 65 2.4.7 Energy and Momentum: Collisions and Billiards 73 2.4.8 Escape from Gravity 74 C HAPTER 3 THERMAL P HYSICS 77 3.1 Introduction 77 3.1.1 Energy Sources 77 3.1.2 Problems 78 3.1.3 Energy Conversions 79 3.2 Ideal Gas 79 3.2.1 First Law of hermodynamics 80 CONTENTS IX 3.2.2 Temperature 81 3.2.3 Pressure 82 3.2.4 Heat Flow 84 3.2.5 Second Law of hermodynamics 84 3.3 Entropy 86 3.3.1 Entropy’s Dual Deinition: Information and hermodynamics 86 3.3.2 Fundamental Property of Entropy 88 3.3.3 hird Law of hermodynamics 92 3.4 Phase Transitions 93 3.4.1 Boiling Water 93 3.4.2 Steam Engines 94 3.4.3 Other Phase Transitions 95 3.5 Random Walks 95 3.5.1 A Random Walk in One Dimension 96 3.5.2 Difusion and Conduction 98 3.5.3 Age of Earth 99 3.5.4 Brownian Motion and Equipartition 102 C HAPTER 4 E LECTROMAGNETISM 105 4.1 Introduction 105 4.2 Electrostatics 105 4.2.1 Atoms and Charge 105 4.2.2 Coulomb’s Law 106 4.2.3 Electric Field 108 4.2.4 Geometry, Forces, and Fields 109 4.2.5 Millikan Oil Drop Experiment 110 4.3 Electricity in Practice 112 4.3.1 An Analogy with Plumbing 112 4.3.2 Voltage and Electric Field 114 4.3.3 Conductors and Insulators 115 4.3.4 Ohm’s Law 115 4.3.5 Charge Storage and Memory: he Capacitor 116 4.3.6 Electrostatic Spark 117 4.3.7 Lightning 119 4.3.8 Batteries 120 4.3.9 Car Batteries 121 4.3.10 Electricity in the Home 122 4.3.11 Electricity and Danger 123 4.4 Magnetism 124 4.4.1 Basic Example 125 4.4.2 Problem with the Basic Example: Relativity 126 4.4.3 Large Magnetic Fields 127 4.4.4 Magnetic Energy and Pressure 128 4.4.5 Motion in a Magnetic Field 129 4.4.6 Orbit Period 132 4.4.7 Magnetic Materials 134 X CONTENTS 4.4.8 Compass 135 4.4.9 Magnetic Moment 136 4.4.10 Force between Magnets 137 4.4.11 Electric Motors and Generators 138 4.5 Uniication of Electricity and Magnetism: Maxwell and Faraday 140 4.5.1 Maxwell’s Equations 140 4.5.2 Faraday’s Law 140 C HAPTER 5 WAV E S 147 5.1 Introduction 147 5.2 Common Features of Waves 147 5.2.1 Wavelength, Frequency, Speed, Amplitude, and Energy 147 5.2.2 Sound in Solids 149 5.2.3 Sound in Gas 150 5.2.4 Electromagnetic Waves 151 5.3 Sound Waves in Air 151 5.3.1 Sound Wave Physics Background 151 5.3.2 Sound We Hear 155 5.3.3 Sound Curiosities 158 5.3.4 Sound Danger 162 5.4 Light Waves and Geometric Optics 163 5.4.1 Speed of Light 163 5.4.2 Pierre de Fermat and the Geometry of Light 164 5.4.3 Is Light Really a Wave? 170 5.5 Electromagnetic Waves 173 5.5.1 Electromagnetic Wave Properties 173 5.5.2 Example Electromagnetic Waves: Frequencies Above and Below the Visible 173 5.5.3 Energy and Momentum of Electromagnetic Waves: Heat and a Push from the Sun 175 5.5.4 Polarization of Electromagnetic Waves and Its Applications 177 5.5.5 Electromagnetic Wave Doppler Efect and the Universe 182 5.5.6 Radiation and Scattering of Electromagnetic Waves 182 5.5.7 Vision: he Perception of Electromagnetic Waves 184 C HAPTER 6 Q UANTUM 191 6.1 Introduction 191 6.2 What Good Is Quantum Mechanics? 193 6.3 Problems with Classical Physics 193 6.3.1 Atoms 193 6.3.2 X-rays 195 CONTENTS XI 6.3.3 Radioactivity 195 6.3.4 he Two “Mystery” Gateways to Quantum Mechanics 196 6.4 Photons 196 6.4.1 he Mysteries 197 6.4.2 he Solutions 200 6.4.3 Photon Properties 202 6.4.4 Other Harmonic Oscillators 204 6.5 Particles and Waves 204 6.5.1 de Broglie Hypothesis 204 6.5.2 Quantized Angular Momentum 205 6.5.3 Hydrogen Atom 206 6.5.4 Probability and Uncertainty 208 6.5.5 Schrodinger Equation 214 6.6 What Is 137? 215 6.6.1 Curious Facts 215 6.6.2 A Universal Number 216 6.6.3 No Explanation 216 6.6.4 Anthropic Principle 217 6.6.5 Numerology 217 6.7 Magnetism and Spin 218 6.7.1 Orbital Magnetism (Ignoring Spin) 218 6.7.2 Spin 219 6.7.3 Magnetic Resonance 220 6.8 Many Particles 220 6.8.1 Helium 221 6.8.2 Identical Electrons 222 6.8.3 Pauli Exclusion Principle 222 C HAPTER 7 M AT E RI A L S AND D EVICES 225 7.1 Introduction 225 7.2 Materials 226 7.2.1 Solid, Liquid, Gas 226 7.2.2 Crystalline Solids 227 7.2.3 hree Important Crystals: Salt, Diamond, and Copper 229 7.2.4 Imperfect Crystals and Disordered Solids 231 7.2.5 Metals and Insulators 234 7.2.6 Special Properties 234 7.3 Devices and Applications 238 7.3.1 Microwave Ovens 238 7.3.2 Lasers 240 7.3.3 Semiconductors and the Amazing p–n Junction 242 7.3.4 Transistors 246 7.3.5 Computers 248 7.3.6 Sound Reproduction 252 XII CONTENTS C HAPTER 8 RE L ATI V IT Y 259 8.1 Introduction 259 8.2 Special Relativity 259 8.2.1 A Famous Equation: Mass and Energy 259 8.2.2 he Energy Triangle: Nothing Goes Faster than Light 261 8.2.3 Speed Is Confusing 263 8.2.4 Time and Simultaneity 263 8.2.5 Muons: Time Dilation and Length Contraction 265 8.2.6 Relativity Beyond Mechanics 267 8.3 General Relativity 268 8.3.1 Red Shifts and Black Holes 268 8.3.2 Equivalence Principle and Light Bending 270 8.3.3 Cosmology 272 8.4 he Meaning of It All 278 C HAPTER 9 N UCLEUS 279 9.1 Introduction 279 9.2 Nuclear Properties 279 9.2.1 Size 279 9.2.2 Mass 279 9.2.3 Isotopes 280 9.2.4 Energies 281 9.3 Radioactivity 282 9.3.1 Alpha, Beta, and Gamma Radioactivity 282 9.3.2 Alpha Decay and Tunneling 283 9.3.3 Beta Decay and Carbon-14 Dating 285 9.3.4 Gamma Decay and the Mossbauer Efect 288 9.4 Fission, Fusion, Nuclear Power, and Bombs 289 9.4.1 Fission 289 9.4.2 Fusion 289 9.4.3 Bombs and Ethics 290 9.4.4 Controlled Fusion