Physics for Scientists and Engineers 8ed - ch22 - end of chapter questions

Physics for Scientists and Engineers 8ed - ch22 - end of chapter questions

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Questions W denotes answer available in Student Solutions Manual/Study Guide; O denotes objective question 1. What are some factors that affect the efficiency of automobile engines? 2. O Consider cyclic processes completely characterized by each of the following net energy inputs and outputs. In each case, the energy transfers listed are the only ones occurring. Classify each process as (a) possible, (b) impossible according to the first law of thermodynamics, (c) impossible according to the second law of thermodynamics, or (d) impossible according to both the first and second laws. (i) Input is 5 J of work and output is 4 J of work. (ii) Input is 5 J of work and output is 5 J of energy transferred by heat. (iii) Input is 5 J of energy transferred by electrical transmission and output is 6 J of work. (iv) Input is 5 J of energy transferred by heat and output is 5 J of energy transferred by heat. (v) Input is 5 J of energy transferred by heat and output is 5 J of work. (vi) Input is 5 J of energy transferred by heat and output is 3 J of work plus 2 J of energy transferred by heat. (vii) Input is 5 J of energy transferred by heat and output is 3 J of work plus 2 J of energy transferred by mechanical waves. (viii) Input is 5 J of energy transferred by heat and output is 3 J of work plus 1 J of energy transferred by electromagnetic radiation. 3. A steam-driven turbine is one major component of an electric power plant. Why is it advantageous to have the temperature of the steam as high as possible? 4. Does the second law of thermodynamics contradict or correct the first law? Argue for your answer. 5. “The first law of thermodynamics says you can’t really win, and the second law says you can’t even break even.” Explain how this statement applies to a particular device or process; alternatively, argue against the statement. 6. O The arrow OA in the PV diagram shown in Figure Q22.6 represents a reversible adiabatic expansion of an ideal gas. The same sample of gas, starting from the same state O , now undergoes an adiabatic free expansion to the same final volume. What point on the diagram could represent the final state of the gas? (a) the same point A as for the reversible expansion (b) point B (c) point C (d) any of these choices (e) none of these choices 7. Give various examples of irreversible processes that occur in nature. Give an example of a process in nature that is nearly reversible. 8. The device shown in Figure Q22.8, called a thermoelectric converter, uses a series of semiconductor cells to transform internal energy to electric potential energy, which we will study in Chapter 25. In the photograph at the left, both legs of the device are at the same temperature and no electric potential energy is produced. When one leg is at a higher temperature than the other as shown in the photograph on the right, however, electric potential energy is produced as the device extracts energy from the hot reservoir and drives a small electric motor. (a)
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This note was uploaded on 05/22/2010 for the course PHYS 2326 taught by Professor Staff during the Summer '08 term at HCCS.

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Physics for Scientists and Engineers 8ed - ch22 - end of chapter questions

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