Physics for Geologists, Second edition

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Gravity 41 Figure 3.9 The siphon at work. When one container is raised, it acquires potential energy due to the difference in elevation, h, and this potential energy is realized by moving the water from the higher to the lower container. larger pressure in the longer arm of the tube. Clearly there is no pressure discontinuity inside the tube, and we can assume that the smallest pressure in the tube is sensibly at the crest. The pressure inside the tube at the water levels of the containers is the same on both sides - the source and the destination both being at atmospheric pressure at the surfaces of the water. The siphon can be explained in terms of the weight of fluid in the two arms of the tube, where clearly the longer arm has a greater weight of water than the shorter. The heavier side sucks the fluid from the lighter. Again, this has a limit due to the 'vacuum' created if the tube is sufficiently high. This is a valid argument <strong>for</strong> liquids, but it still comes down to energy not pressure. You will remember that the dimensions of energy are a <strong>for</strong>ce or weight times a height above an arbitrary horizontal datum, such as the table top. So the energy of the water in the higher container is greater than that of the water in the lower container, and the extra weight in the longer tube sucks the water from the shorter tube. The same principles apply to a chain passing from one bucket to another over a sheave or pulley. If you lift one bucket, the chain starts moving into the lower bucket. Energy and weight are involved, but not pressure. It does not matter how much chain is in the buckets: it is the relative energy in the chain on either side of the sheave or pulley that matters. To move anything requires energy and work. Copyright 2002 by Richard E. Chapman
4 Optics Light is an electromagnetic radiation. In some respects it behaves as waves; in others, as particles. Its speed in space, cg, is 299 792.4 km s-I, as is the speed of other types of electromagnetic radiation. This is an absolute constant, but light travels rather more slowly in air, much more slowly in transparent mate- rials such as crystals, glass and water. Radio waves are near one end of the range of electromagnetic radiations (wavelength h greater than 30 cm, frequency u less than lo9 Hz): y-rays are near the other end (h less than 10-l2 m, frequency greater than 100 x 1018 Hz). Within the visible range of light, there is a visible spectrum ranging from the longer-wavelength red to the shorter- wavelength violet, through orange, yellow, green, blue and indigo. h,,d is about 700 x lop9 m or 700 nm; hVi,l,, is about 400 nm. Outside this visible spectrum are infrared and ultraviolet. Infrared can be detected on photo- graphic film, and by its heat: ultraviolet can be detected because it excites light in the visible spectrum from some minerals and organic substances. The same relationship between wavelength, h, speed, c and frequency, u (the Greek letter nu), exists in electromagnetic radiation as in other waves, that is where c is the speed of light (but not necessarily as large as co). However, electromagnetic radiation does not always behave as waves. In that case, there is a relationship between the photon quantum energy E, the frequency of light, and Planck's constant, h, E = nhu, (4-2) where n is an integer. This is the basis of the quantum theory, initiated by Max Planck in 1900 - but we shall not go into it. Black objects are black because black absorbs practically all wavelengths that fall on it. White objects are white because white reflects practically all wavelengths that fall on it. Copyright 2002 by Richard E. Chapman
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Physics for Geologists Second editi
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Copyright 2002 by Richard E. Chapma
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... vlii Contents Polarization 47 L
Page 7 and 8: Figures Copyright 2002 by Richard E
Page 9 and 10: Tables Copyright 2002 by Richard E.
Page 11 and 12: xiv Preface waves diminishes with d
Page 13 and 14: xvi Preface provides. This book is
Page 15 and 16: xviii Acknowledgements to K. Whaler
Page 17 and 18: xx Symbols mass refractive index bu
Page 19 and 20: 2 Basic concepts Table 1.1 Dimensio
Page 21 and 22: 4 Basic concepts Table 1.2 Basic SI
Page 23 and 24: 6 Basic concepts pascal (Pa) and si
Page 25 and 26: 8 Basic concepts all the relevant d
Page 27 and 28: 10 Basic concepts relating them by
Page 29 and 30: 2 Force The dimensions of force are
Page 31 and 32: 14 Force The ratio of the Moon's ac
Page 33 and 34: 16 Force Figure 2.1 The sum of the
Page 35 and 36: 18 Force When a motorcycle takes a
Page 37 and 38: 20 Force Figure 2.3 Torque is the p
Page 39 and 40: 22 Force How does momentum differ f
Page 41 and 42: 24 Force the weights - that is, the
Page 43 and 44: 26 Force Figure 2.6 Wall-sticking i
Page 45 and 46: 3 Gravity Universal gravity When di
Page 47 and 48: 30 Gravity are significant to geolo
Page 49 and 50: 32 Gravity Figure 3.2 The tractive,
Page 51 and 52: 34 Gravity Mean sea level It might
Page 53 and 54: 36 Gravity The benefits of space fl
Page 55 and 56: 38 Gravity Figure 3.6 Profile of th
Page 57: 40 Gravity Figure 3.8 The siphon at
Page 61 and 62: 44 Optics Figure 4.2 Refraction. (a
Page 63 and 64: 46 Optics The coeficient of reflect
Page 65 and 66: 48 Optics only the light oscillatin
Page 67 and 68: 50 Optics called Iceland Spar. Two
Page 69 and 70: 52 Optics Diffraction If you shine
Page 71 and 72: 54 Optics Figure 4.7 Geometrical op
Page 73 and 74: 56 Optics Figure 4.9 The mirrors in
Page 75 and 76: 5 Atomic structure and age-dating P
Page 77 and 78: 60 Atomic structure and age-dating
Page 83 and 84: 66 Electromagnetic radiation radiat
Page 85 and 86: 68 Electromagnetic radiation Source
Page 87 and 88: Heat and heat flow The noun heat ha
Page 89 and 90: 72 Heat and heat flow Second Law: A
Page 91 and 92: 8 Electricity and magnetism Electri
Page 93 and 94: Electricity and magnetism 77 Figure
Page 95 and 96: Electricity and magnetism 79 rivett
Page 97 and 98: Electricity and magnetism 8 1 defin
Page 99 and 100: Electricity and magnetism 83 is kno
Page 101 and 102: 9 Stress and strain Pressure, p, is
Page 103 and 104: Stress and strain 87 than some natu
Page 105 and 106: These three elastic constants are r
Page 107 and 108: Stress and strain 91 Figure 9.1 New
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Stress and strain 93 Figure 9.2 Com
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Stress and strain 95 Figure 9.3 Ide
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Fracture Stress and strain 97 We fo
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Stress and strain 99 from which we
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10 Sea waves The nature of water wa
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Sea waves 103 Figure 10.1 Wave moti
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Sea waves 105 refraction by islands
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Acoustics: sound and other waves 10
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Acoustics: sound and other waves 10
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12 Fluids and fluid flow Introducti
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Fluids and fluid flow 1 13 Figure 1
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Fluids and fluid flow 115 Figure 22
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Fluids and fluid flow 117 and the f
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water above a vertical thickness h
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Fluids and fluid flow 121 where V i
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Fluids and fluid flow 123 ardentes,
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Fluids and fluid flow 125 Figure 12
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- 14 $ 12 E 10 K .- 3 8 r cll + 6 0
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Fluids and fluid flow 129 the liqui
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Some dangers of mathematical statis
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Appendix 139 What would happen if y
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Notes 141 and since x is very large
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References Allum, J. A. E. (1966) P
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References 145 -(1950) 'Mechanism o
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Further reading 147 Trigg, G. L. an
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Physics for Geologists, Second edition

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