| Preface |
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ix | |
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1 | (8) |
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1 | (1) |
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1.2 What This Book Is About |
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2 | (4) |
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1.3 A Physical versus a Mathematical Solution: An Example |
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6 | (2) |
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8 | (1) |
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2 The Pythagorean Theorem |
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9 | (18) |
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9 | (1) |
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2.2 The "Fish Tank" Proof of the Pythagorean Theorem |
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9 | (3) |
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2.3 Converting a Physical Argument into a Rigorous Proof |
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12 | (2) |
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2.4 The Fundamental Theorem of Calculus |
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14 | (1) |
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2.5 The Determinant by Sweeping |
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15 | (1) |
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2.6 The Pythagorean Theorem by Rotation |
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16 | (1) |
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2.7 Still Water Runs Deep |
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17 | (2) |
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2.8 A Three-Dimensional Pythagorean Theorem |
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19 | (2) |
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2.9 A Surprising Equilibrium |
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21 | (1) |
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2.10 Pythagorean Theorem by Springs |
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22 | (1) |
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2.11 More Geometry with Springs |
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23 | (1) |
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2.12 A Kinetic Energy Proof: Pythagoras on Ice |
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24 | (1) |
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2.13 Pythagoras and Einstein? |
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25 | (2) |
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27 | (49) |
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3.1 The Optical Property of Ellipses |
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28 | (3) |
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3.2 More about the Optical Property |
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31 | (1) |
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3.3 Linear Regression (The Best Fit) via Springs |
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31 | (3) |
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3.4 The Polygon of Least Area |
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34 | (2) |
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3.5 The Pyramid of Least Volume |
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36 | (3) |
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3.6 A Theorem on Centroids |
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39 | (1) |
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3.7 An Isoperimetric Problem |
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40 | (4) |
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44 | (3) |
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47 | (1) |
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3.10 The Best Spot in a Drive-In Theater |
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48 | (3) |
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51 | (1) |
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3.12 Fermat's Principle and Snell's Law |
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52 | (5) |
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3.13 Saving a Drowning Victim by Fermat's Principle |
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57 | (2) |
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3.14 The Least Sum of Squares to a Point |
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59 | (1) |
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3.15 Why Does a Triangle Balance on the Point of Intersection of the Medians? |
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60 | (1) |
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3.16 The Least Sum of Distances to Four Points in Space |
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61 | (2) |
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3.17 Shortest Distance to the Sides of an Angle |
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63 | (1) |
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3.18 The Shortest Segment through a Point |
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64 | (1) |
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3.19 Maneuvering a Ladder |
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65 | (2) |
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3.20 The Most Capacious Paper Cup |
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67 | (2) |
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3.21 Minimal-Perimeter Triangles |
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69 | (3) |
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3.22 An Ellipse in the Corner |
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72 | (2) |
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74 | (2) |
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4 Inequalities by Electric Shorting |
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76 | (8) |
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76 | (2) |
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4.2 The Arithmetic Mean Is Greater than the Geometric Mean by Throwing a Switch |
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78 | (2) |
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4.3 Arithmetic Mean ≥ Harmonic Mean for n Numbers |
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80 | (1) |
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4.4 Does Any Short Decrease Resistance? |
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81 | (2) |
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83 | (1) |
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5 Center of Mass: Proofs and Solutions |
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84 | (15) |
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84 | (1) |
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5.2 Center of Mass of a Semicircle by Conservation of Energy |
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85 | (2) |
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5.3 Center of Mass of a Half-Disk (Half-Pizza) |
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87 | (1) |
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5.4 Center of Mass of a Hanging Chain |
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88 | (1) |
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5.5 Pappus's Centroid Theorems |
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89 | (3) |
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92 | (2) |
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5.7 Three Applications of Ceva's Theorem |
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94 | (2) |
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96 | (3) |
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99 | (10) |
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6.1 Area between the Tracks of a Bike |
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99 | (2) |
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6.2 An Equal-Volumes Theorem |
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101 | (1) |
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6.3 How Much Gold Is in a Wedding Ring? |
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102 | (2) |
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104 | (2) |
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6.5 Finding d/dt sin t and d/dt cos t by Rotation |
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106 | (2) |
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108 | (1) |
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7 Computing Integrals Using Mechanics |
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109 | (6) |
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7.1 Computing ∫10 by x dx/1-x2 Lifting a Weight |
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109 | (2) |
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7.2 Computing ∫x0 sin tdt with a Pendulum |
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111 | (1) |
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7.3 A Fluid Proof of Green's Theorem |
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112 | (3) |
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8 The Euler-Lagrange Equation via Stretched Springs |
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115 | (5) |
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8.1 Some Background on the Euler-Lagrange Equation |
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115 | (2) |
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8.2 A Mechanical Interpretation of the Euler-Lagrange Equation |
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117 | (1) |
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8.3 A Derivation of the Euler-Lagrange Equation |
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118 | (1) |
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8.4 Energy Conservation by Sliding a Spring |
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119 | (1) |
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9 Lenses, Telescopes, and Hamiltonian Mechanics |
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120 | (13) |
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9.1 Area-Preserving Mappings of the Plane: Examples |
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121 | (1) |
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121 | (2) |
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9.3 A (Literally!) Hand-Waving "Proofv of Area Preservation |
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123 | (1) |
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9.4 The Generating Function |
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124 | (1) |
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9.5 A Table of Analogies between Mechanics and Analysis |
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125 | (1) |
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9.6 "The Uncertainty Principle" |
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126 | (1) |
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9.7 Area Preservation in Optics |
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126 | (3) |
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9.8 Telescopes and Area Preservation |
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129 | (2) |
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131 | (2) |
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10 A Bicycle Wheel and the Gauss-Bonnet Theorem |
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133 | (15) |
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133 | (2) |
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10.2 The Dual-Cones Theorem |
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135 | (3) |
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10.3 The Gauss-Bonnet Formula Formulation and Background |
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138 | (4) |
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10.4 The Gauss-Bonnet Formula by Mechanics |
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142 | (1) |
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10.5 A Bicycle Wheel and the Dual Cones |
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143 | (3) |
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10.6 The Area of a Country |
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146 | (2) |
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11 Complex Variables Made Simple(r) |
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148 | (13) |
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148 | (1) |
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11.2 How a Complex Number Could Have Been Invented |
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149 | (1) |
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11.3 Functions as Ideal Fluid Flows |
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150 | (3) |
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11.4 A Physical Meaning of the Complex Integral |
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153 | (1) |
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11.5 The Cauchy Integral Formula via Fluid Flow |
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154 | (2) |
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11.6 Heat Flow and Analytic Functions |
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156 | (1) |
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11.7 Riemann Mapping by Heat Flow |
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157 | (2) |
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11.8 Euler's Sum via Fluid Flow |
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159 | (2) |
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Appendix. Physical Background |
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161 | (22) |
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161 | (1) |
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162 | (2) |
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164 | (1) |
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165 | (1) |
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165 | (1) |
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A.6 The Equilibrium of a Rigid Body |
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166 | (1) |
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167 | (2) |
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169 | (1) |
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A.9 The Moment of Inertia |
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170 | (2) |
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172 | (1) |
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172 | (1) |
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173 | (1) |
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A.13 Resistance and Ohm's Law |
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174 | (1) |
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A.14 Resistors in Parallel |
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174 | (1) |
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175 | (1) |
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A.16 Power Dissipated in a Resistor |
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176 | (1) |
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A.17 Capacitors and Capacitance |
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176 | (1) |
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A.18 The Inductance: Inertia of the Current |
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177 | (2) |
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A.19 An Electrical-Plumbing Analogy |
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179 | (2) |
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181 | (2) |
| Bibliography |
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183 | (2) |
| Index |
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185 | |