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Unformatted text preview: Chapter 12, The Laws of Thermodynamics C HAPTER 12 Conceptual Problems C1. On a PV diagram, 2 curves are plotted, both starting at the same point ( P 1 , V 1 ) and both ending at the same increased volume ( V 2 ). One curve is for an isothermal process; the other is for an adiabatic process. Except for the common starting point, which curve is the upper one? a. The isothermal process curve will always be the upper one. b. The adiabatic process curve will always be the upper one. c. Since they start at the same point and end at the same volume, they will coincide. d. The isothermal one will start out higher, but the adiabatic one will eventually cross it. C2. At the dice factory, sets of novelty dice are created where a side with 7 dots replaces the single dot side. The sides then range from 2 to 7 instead of the usually 1 to 6. Using such dice for a game of craps, what will be the most probable roll? a. 7, this change in dots results in the same most probable value. b. 7.5 c. 8 d. 9 C3. On a PV diagram, 2 curves are plotted, both starting at the same point and both ending at the same final increased volume. One curve is for an isothermal process; the other is for an adiabatic process. What does the area between these two curves represent? a. Q absorbed by the isothermal process. b. W done by the adiabatic process. c. U for the isothermal process. d. Neither Q , W , nor U for either of the processes is represented. C4. Three Carnot engines operate between temperature reservoirs as follows: Engine A: T h = 1 300 K, T c = 1 000 K; Engine B: T h = 1 000 K, T c = 700 K; Engine C: T h = 650 K, T c = 500 K. Which two engines have the same thermal efficiency? a. A and B b. B and C c. A and C d. No two have the same thermal efficiency. C5. In an isovolumetric process where the pressure increases, are the heat absorbed, work done by the system, and the change in internal energy of the system positive, negative, or zero? a. Q is +, W is +, and U is +. b. Q is +, W is , and U is 0. c. Q is +, W is 0, and U is +. d. Q is , W is 0, and U is . 12.1 Work in Thermodynamic Processes 179 Chapter 12, The Laws of Thermodynamics 1. The volume of an ideal gas changes from 0.40 to 0.55 m 3 although its pressure remains constant at 50 000 Pa. What work is done on the system by its environment? a. 7 500 J b. - 200 000 J c. 7 500 J d. 200 000 J 2. During an isobaric process which one of the following does not change? a. volume b. temperature c. internal energy d. pressure 3. Area on a P-V diagram has units associated with: a. energy. b. momentum. c. temperature. d. change in temperature. 4. What is the work done on the gas as it expands from pressure P 1 and volume V 1 to pressure P 2 and volume V 2 along the indicated straight line?...
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- Spring '09