Figure 4. 1: U. S. household energy consumption by end use Figure 4.1: U.S. household energy consumption by end use. 1 Quad = 1015 Btu. Fig. 4-1, p. 98

Figure 4. 2: Relationship between work and heat Figure 4.2: Relationship between work and heat. A temperature change in the water can be caused either by letting the weight drop (causing the blades to rotate) or by adding heat from the gas burner. Fig. 4-2, p. 99

Figure 4.3: Bicycle pump. Work done on the air in pushing the handle down results in an increase in the air’s thermal energy. W = F × d = ΔTE. Fig. 4-3, p. 100

Table 4-1, p. 101

Table 4-2, p. 102

Figure 4. 4: Thermal energy Figure 4.4: Thermal energy. (a) If both brick assemblies are heated in a kiln for several hours, they will have the same temperature, but the larger array will store nine times as much thermal energy as the smaller one. Fig. 4-4a, p. 103

Figure 4. 4: Thermal energy Figure 4.4: Thermal energy. (b) A 1-lb sample of water stores about five times as much thermal energy as 1 lb of rocks at the same temperature, because water has a higher specific heat. Fig. 4-4b, p. 103

Figure 4.5: Water has a high specific heat. Fig. 4-5, p. 103

Figure 4.6: Changes of phase for water. Fig. 4-6, p. 105

Figure 4. 7: Heat flows when there is a temperature difference ΔT Figure 4.7: Heat flows when there is a temperature difference ΔT. In this case, ΔT = 70° − 50° = 20°F. Fig. 4-7, p. 106

Figure 4.8: Heat is transferred by conduction through the metal spoon from the hot coffee to the colder fingers. Fig. 4-8, p. 107

Figure 4. 9: Heat flow through a wall by conduction Figure 4.9: Heat flow through a wall by conduction. The rate Qc/t at which heat energy is transferred through the material depends on the temperatures on either side (T1 and T2), the wall’s area A, its thickness δ, and its thermal conductivity k. Fig. 4-9, p. 108

Figure 4.10: Percentage of energy saved by lowering the thermostat from 72°F to the values shown on the curved lines, for the time periods shown. Fig. 4-10, p. 108

Figure 4.11: Convection currents in water. Fig. 4-11, p. 109

Figure 4.12: Heat transfer through a double-pane window. Fig. 4-12, p. 110

Figure 4.13: Solar air heater for use in a window. Fig. 4-13, p. 110

Figure 4.14: Waves generated by moving the end of a rope. Fig. 4-14, p. 112

Figure 4.15: The electromagnetic spectrum, shown as a function of wavelength. Fig. 4-15, p. 112

Figure 4.16: The spectrum of radiation emitted from the sun and the earth. The vertical scales for each spectrum are different, as the intensity of radiation from the sun is many times greater than that from the earth. Fig. 4-16, p. 113

Figure 4.17: The equilibrium temperature of an object is maintained if the energy input is equal to the energy output. Fig. 4-17, p. 114

Figure 4.18: A hot-water radiator as an illustration of heat transfer via conduction, convection, and radiation. Fig. 4-18, p. 115

Figure 4.19: A heat engine transforms heat into work. Fig. 4-19, p. 116

Table 4-3, p. 117

Figure 4. 20: Ocean Thermal Energy Conversion (OTEC) Figure 4.20: Ocean Thermal Energy Conversion (OTEC). The temperature difference between waters on the top of the water and down deep allows one to construct a heat engine. Fig. 4-20, p. 118

Figure 4.21: Impossibilities according to the second law of thermodynamics. (a) Heat withdrawn from the table is converted into mechanical energy—the kinetic energy of the block. Fig. 4-21a, p. 119

Figure 4.21: Impossibilities according to the second law of thermodynamics. (b) Heat from sea water is converted into electrical energy (the resulting ice cubes are discarded). Fig. 4-21b, p. 119

p. 128