Great news. I am on my last on-line physics module before the Holiday season comes along. I have posted and answered my self-assessment questions (answers appear with *asterisk). Again, please let me know the ones I answered correctly on and the ones I missed (I think there are many because this material was difficult) give a gentle push in the right direction (i.e. a formula, hint,). I will then provide my thought process on why I answered the way I did. Thanks to everyone who has helped me in the past three months. Happy Holiday! 1. The second law of thermodynamics says that: a. the energy of an isolated system is conserved. b. it is impossible to build a heat engine that can do mechanical work by extracting thermal energy that does not also exhaust heat to the surroundings. c. it is impossible to reach the absolute zero of temperature. d. it is impossible to build a heat engine that does more mechanical work than the thermal energy it consumes.* 2. Many people have tried to build perpetual-motion machines. Our study of physics tells us that perpetual-motion machines are: a. theoretically possible, but difficult to build. b. theoretically possible if they do not violate the first law of thermodynamics. c. theoretically possible, but would be very inefficient. d. not possible to build.* 3. The efficiency of an ideal heat engine can be improved by __________ the input temperature and __________ the exhaust temperature. a. increasing ... increasing b. increasing ... decreasing* c. decreasing ... increasing d. decreasing ... decreasing 4. A heat engine takes in 600 J of energy at 1000 K and exhausts 300 J at 400 K. What is the maximum theoretical efficiency of this engine? a. 40% b. 50%* c. 60% d. 80% 5. An engine has an efficiency of 40%. How much energy must be extracted to do 900 J of work? a. 360 J b. 900 J c. 2250 J d. 3600 J* 6. The second law of thermodynamics says that: a. the energy of an isolated system is conserved. b. it is impossible to build a refrigerator that can transfer heat from a lower temperature region to a higher temperature region without expending mechanical work. c. it is impossible to reach the absolute zero of temperature. d. it is impossible to build a refrigerator that exhausts more heat than the mechanical work required to operate it.* 7. An air-conditioner mechanic is testing a unit by running it on the workbench in an isolated room? What happens to the temperature of the room? a. It increases.* b. It decreases. c. It stays the same. 8. The second law of thermodynamics: a. says that it is impossible to reach the absolute zero of temperature. b. says that the entropy of a system tends to increase.* c. is the basis for the definition of temperature. d. is the basis for the definition of internal energy. 9. In which of the systems listed below is the entropy decreasing? a. A gas is cooled.* b. A plate is shattered. c. An egg is scrambled. d. A drop of dye diffuses in a cup of water. 10. A cold piece of metal is dropped into an insulated container of hot water. After the system has reach an equilibrium temperature, the: a. entropy of the metal has decreased. b. entropy of the water has increased. c. net change in entropy of the system is zero.* d. entropy of the system has increased.