25. When heating water on a stove, a full pan of water takes longer to reach the boiling point than a pan that is half full. Why?

27. In Example 5.5, is it really necessary to know the mass of the concrete block to solve this problem? Put another way, would the answer be different if it was a 10-kg block that was dropped instead of a 5-kg one?

29. The specific heat capacity of water is extremely high. If it were much lower, say, one-fifth as large, what effect would this have on processes such as fighting fires and cooling automobile engines?

31. Describe how changing the air pressure affects the temperature at which water boils.

33. What is saturation density? How does it change when the temperature increases?

35. Wood's metal is an alloy of the elements bismuth, lead, tin, and cadmium that has a melting point of 70C. Describe how it might be used in an automatic sprinkler system for fire suppression.

37. Explain what a heat engine does and what a heat mover does.

39. What is entropy? In general, how does the entropy of a system change with time?

43. Is our society truly facing an "energy crisis," assuming by this term we mean that we are running out of energy? What is happening to our energy resources as a result of the increasing industrialization of the world?

45. Six cylinders each contain the same mass of helium gas but have different volumes and temperatures as given below. All of the containers are made of the same material and stored under the same environmental conditions. Rank the containers according to their pressures from highest to lowest. If any of the containers have the same pressure, give them the same ranking. Explain how you formed your rankings. Container A: T = 200 K; V = 2000 cm3

Container B: T = 300 K; V = 15,000 cm3

Container C: T = 400 K; V = 5000 cm3

Container D: T = 300 K; V = 10,000 cm3

Container E: T = 200 K; V = 4000 cm3

Container F: T = 500 K; V = 10,000 cm3