ME 215 Final Mult. Choice
ME 215 Final Mult. Choice ME 215
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This 4 page Study Guide was uploaded by Haley on Tuesday August 2, 2016. The Study Guide belongs to ME 215 at University of Alabama - Tuscaloosa taught by Dr. Clark Midkiff in Spring 2016. Since its upload, it has received 24 views. For similar materials see Thermodynamics I in Mechanical Engineering at University of Alabama - Tuscaloosa.
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Date Created: 08/02/16
Spring 2016 Multiple Choice Test 1 8. Which of the following is an extensive property? A. Pressure B. Specific volume C. Total volume D. Density 9. Heat is a quantity of energy that can be completely converted into raising a weight. A. True B. False 10. We say that a system is in mechanical equilibrium if there is no tendency for the pressure in the system to change. A. True B. False 11. Mass transfer can occur across the boundary of a control volume/open system. A. True B. False 12. If a rock is the thermodynamic system of interest, when we lift the rock, the system’s work is positive. A. True B. False Test 2 1. If a process is steady state, steady flow, the sum of the mass flow rates into the system equals the sum of the mass flow rates out of the system. a. True b. False 2. A system’s mass, energy, and entropy cannot change over time during a steady process. a. True b. False 3. A heat engine thermal efficiency of 100% satisfies the First Law. a. True b. False 4. A heat engine thermal efficiency of 100% satisfies the Second Law. a. True b. False 5. A cyclic device that takes in heat from a high temperature source, rejects heat to a low temperature source, and performs useful work is a: a. Refrigeration cycle b. Heat pump c. Heat engine d. None of the above 6. The temperature of a thermal reservoir can be easily changed. a. True b. False 7. The sum of the entropy change of the system plus the entropy change of the surroundings during a process cannot be negative. a. True b. False 8. Entropy is generated when heat is transferred from a cold system to warm surroundings. a. True b. False 9. Entropy is generated when work is transferred into a system. a. True b. False 10. Entropy can only be created, not destroyed. a. True b. False 11. Any process that satisfies the First Law of Thermodynamics automatically satisfies the Second Law. a. True b. False 12. If the system’s entropy decreases, the process must violate the Second Law. a. True b. False 13. A cup of coffee… (same as test 4) 14. If a process results in a net increase in the entropy of the universe (system plus surroundings), it is an irreversible process. a. True b. False Test 3 1. At a given T, the phase of H2O will be a superheated vapor if a. P < P SAT b. v < v f c. P > P SAT d. h f h < hg 2. A mixture of ice cubes and liquid water is considered a pure substance. a. True b. False 3. A powerplant takes in heat at a rate of 1000 MW and produces 600 MW of power. The percent thermal efficiency is a. 0% b. 40% c. 60% d. 100% 4. A heat engine takes in 100 Btu of heat and rejects 60 Btu as waste heat. The percent thermal efficiency is a. 0% b. 40% c. 60% d. 100% 5. The term “thermal efficiency” applies to a. A heat pump b. Any heat engine c. A refrigeration cycle d. All of these 6. For H 2 at P = 200 kPa, T SAT= 120.23 °C. If 2 O is at a pressure of 200 kPa and a temperature of 200 °C it is a. Subcooled liquid b. Saturated liquid c. Saturated mixture d. Saturated vapor e. Superheated vapor Test 4 1. The properties u and h depend only on temperature for an ideal gas. a. True b. False 2. We must use the ideal gas table or Air Table for an ideal gas with constant specific heats. a. True b. False 3. An ideal gas is compressed isothermally from 100 kPa to 900 kPa. The change in enthalpy is a. Positive b. Zero c. Negative d. Not enough information 4. Which device extracts work from a steady flow of fluid as pressure drops through the device? a. Pump b. Nozzle c. Compressor d. Turbine e. Diffuser 5. Air flows steadily and is heated essentially at constant pressure through a pipe that is heated by a furnace, as shown to the right. What happens to the mass flow rate of air as it flows through the pipe? a. Mass flow rate increases b. Mass flow rate remains the same c. Mass flow rate decrease d. Need more information 6. Work is a property of the system. a. True b. False
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