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# p101chap11pretest - Chapter 11 Heat Engines and the Second...

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Chapter 11: Heat Engines, and the Second Law of Thermodynamics 1. The second law of thermodynamics says that the total amount of entropy, or randomness, in the universe cannot decrease. However, we see all around us objects that become more ordered - - for example, the development of a biological organism, or water that freezes. The decrease in entropy, or randomness, in such cases does not violate the second law because A. there is always a greater increase in entropy somewhere else. B. energy must be added. C. energy must be removed. D. water and living things do not have entropy. Answer: A 2. Why couldn’t you use an electric motor to turn an electrical generator that in turn provides the electrical energy for the motor? A. No energy converter is 100% efficient. B. Yes, you can do this! C. Motors require AC and generators produce DC. Answer: A 3. Shown below are 4 figures that represent the heat flow in a heat engine. The thickness of the arrows represents the amount of heat flow. Which figure best represents a real heat engine? Answer: B 4. Energy added to a cyclical heat engine A. is completely converted to external work. B. is converted to increased internal energy in the engine plus external work. C. is used to generate work that is greater than the added energy. D. is converted to work and to waste heat. Answer: D A B CD

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5. The primary function of any heat engine is to A. convert work into heat. B. create energy. C. convert heat into work D. destroy energy and replace it with work Answer: C 6. The work performed by a heat engine A. equals the heat energy exhausted from the engine. B. equals the heat energy entering the engine. C. equals the change in the internal energy of the engine. D. equals the net heat flow into the engine. Answer: D 7. The change in internal energy during one complete cycle of a heat engine A. equals the net heat flow into the engine. B. equals zero. C. equals the heat energy exhausted from the engine. D. equals the heat energy entering the engine. Answer: B 8. One important feature of the Carnot cycle is that it A. predicts the maximum efficiency of any engine operating between two temperatures. B. predicts the maximum work output from any real engine. C. predicts the maximum heat exhausted from any real engine. D. is the only real complete cycle which produces work. Answer: A 9. The efficiency of an engine can be defined as the A. total amount of work performed. B. ratio of work done to energy exhausted. C. ratio of work done to energy input.
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## This note was uploaded on 07/10/2008 for the course PHYS 1030 taught by Professor Ross during the Summer '08 term at Northeast State.

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p101chap11pretest - Chapter 11 Heat Engines and the Second...

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