FIG. 4-1 The heat content of a given substance depends upon both its mass and its temperature. A pail of cool water contains more heat than a cup of boiling water.

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FIG. 4-2 A liquid-in-glass thermometer. Mercury or a colored alcohol solution responds to temperature changes to a greater extent than glass does, and so the length of the liquid column is a measure of the temperature of the thermometer bulb.

FIG. 4-4 The color of an object hot enough to glow varies with its temperature roughly as shown here.

                                                                                                           

FIG. 4-6 To raise the temperature of 1 kg of water by 1° C, 4.2kJ of heat must be added to it. The same amount of heat must be removed to cool the water by 1° C.

                                                                                                         

FIG. 4-7 If 4.2 kJ of heat is added to or removed from 1 kg of other substances, their temperatures change by more than the 1°C change produced in water.

FIG. 4-8 The three mechanisms of heat transfer.

FIG. 4-15 Boyle's law: At constant temperature, the volume of a sample of any gas is inversely proportional to the pressure applied to it. Here p1V1 = p2V2 = p3V3.

FIG. 4-16 Charles's law: At constant pressure, the volume of a gas sample is directly proportional to its absolute temperature TK, where TK = TC + 273°. Here V1/T1 = V2/T2 = V3/T3.

FIG. 4-17 The absolute temperature scale.

                                                   

FIG. 4-22 According to the kinetic theory of gases, at absolute zero the molecules of a gas would not move. More advanced theories show that even at 0 K a very slight movement will persist.

FIG. 4-24 Molecular models of a solid, a liquid, and a gas. The molecules of a solid are firmly attached to one another; those of a liquid can move about but stay close together; those of a gas have no restrictions on their motion.

FIG. 4-29 The orderly arrangement of particles in a crystalline solid changes to the random arrangement of particles in a liquid when enough energy is supplied to the solid to overcome the bonding forces within it.

FIG. 4-26 Evaporation. Alcohol evaporates more rapidly than water because the attractive forces between its molecules are smaller. In each case, the faster molecules escape. Hence the average kinetic energy of the remaining molecules is lower and the liquid temperature drops.

FIG. 4-27 The heat of vaporization of water is 2260 kJ/kg.

FIG. 4-30 A graph of the temperature of 1 kg of water, originally ice at -50° C, as heat is added to it.

FIG. 4-33 A heat engine converts part of the heat flowing from a hot reservoir to a cold one into work. A refrigerator extracts heat from a cold reservoir and delivers it to a hot one by doing work that is converted into heat.