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# A 4 mole ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment. How

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1. A 4 mole ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment. How much heat is received by the system? • -20 J • zero • +5 J • +20 J

2. A 5 mole ideal gas system undergoes an adiabatic free expansion, going from an initial volume of 10 liters to a final volume of 20 liters. How much work is done by the system during this adiabatic free expansion? • -50 J • -10 J • zero • +50 J

3. A heat engine receives 6000 J of heat from its combustion process and loses 4000 J through the exhaust and friction. What is its efficiency? • 33% • 40% • 67% • 73%

4. If a heat engine has an efficiency of 30% and its power output is 600 W, what is the rate of heat input from the combustion phase? • 1800 W • 2400 W • 2000 W • 3000 W

5. A steam turbine operates at a boiler temperature of 450 K and an exhaust temperature of 300 K. What is the maximum theoretical efficiency of this system? • 24 • 50 • 33 • 67

6. A 4 mole ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment. What is its change in internal energy? • -20 J • -5 J • zero • +20 J

7. The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following? • hot reservoir temperature only • cold reservoir temperature only • both hot and cold reservoir temperatures • none of these choices are valid

8. During an isobaric process which one of the following does not change? • volume • temperature • internal energy • pressure

9. A 2 mole ideal gas system is maintained at a constant volume of 4 liters; if 100 J of heat is added, what is the work done by the system? • zero • 5.0 J • 6.7 J • 20 J

10. A 2 mole ideal gas system is maintained at a constant volume of 4 liters; if 100 J of heat is added, what is the change in internal energy of the system? • zero • 50 J • 67 J • 100 J

11. According to the second law of thermodynamics, which of the following applies to the heat received from a high temperature reservoir by a heat engine operating in a complete cycle? • must be completely converted to work • equals the entropy increase • converted completely into internal energy • cannot be completely converted to work

12. An adiabatic free expansion refers to the fact that • no heat is transferred between a system and its surroundings. • the pressure remains constant. • the temperature remains constant. • the volume remains constant.

13. According to the first law of thermodynamics, the difference in heat gained by a system and the work done by that same system is equivalent to which of the following? • entropy change • internal energy change • temperature change • specific heat

14. If an ideal gas does positive work on its surroundings, then which one of the following choices may be assumed with regard to the gas? • temperature increases • volume increases • pressure increases • internal energy decreases

15. In an isovolumetric process by an ideal gas, the system's heat gain is equivalent to a change in which one of the following? • temperature • volume • pressure • internal energy

16. A one kilogram chunk of ice at 0°C melts, absorbing 80,000 cal of heat in the process. Which of the following best describes what happens to this system? • increased entropy • lost entropy • entropy maintained constant • work converted to energy

17. According to the second law of thermodynamics, for any process that may occur within an isolated system, which of the following choices applies? • entropy remains constant • entropy increases • entropy decreases • none of these choices applies

18. Which of the following choices is an appropriate unit for measuring entropy changes? • joule-K • newton-K • joule/s • joule/K

19. An electrical power plant manages to send 88% of the heat produced in the burning of fossil fuel into the water-to-steam conversion. Of the heat carried by the steam, 40% is converted to the mechanical energy of the spinning turbine. Which of the following choices best describes the overall efficiency of the heat-to-work conversion in the plant (as a percentage)? • greater than 88% • 64% • less than 40% • 40%

20. If one could observe the individual atoms making up a piece of matter and note that during a process of change their motion somehow became more orderly, then one may assume which of the following in regard to the system? • increases in entropy • decreases in entropy • gains in thermal energy • positive work done on

21. Which of the following choices best corresponds to what is required by the second law of thermodynamics for any process taking place in an isolated system? • entropy decreases • entropy remains constant • entropy increases • entropy equals work done

22. An ideal gas is maintained at a constant pressure of 70,000 N/m2 during an isobaric process while its volume decreases by 0.2 m3 . What work is done by the system on its environment? • 14,000 J • 350,000 J • -14,000 J • -35,000 J

23. In an isothermal process for an ideal gas system (where the internal energy doesn't change), which of the following choices best corresponds to the value of the work done by the system? • its heat intake • twice its heat intake • the negative of its heat intake • twice the negative of its heat intake

24. A system which receives 70 J of heat from its environment and does 20 J of work will have what net change in its internal energy? • 90 J • 50 J • zero • -70 J

25. A heat engine performs 2000 J of work while rejecting 5000 J of heat to the cold-temperature reservoir. What is the efficiency of the engine? • 71.4% • 60.0% • 40.0% • 28.6%

26. A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 500 K and 200 K will have what maximum efficiency? • 60 • 50 • 40 • 30

27. An 800 MW electric power plant has an efficiency of 30%. It loses its waste heat in large cooling towers. Approximately how much waste heat (in MJ) is discharged to the atmosphere per second? • 1200 MJ • 1800 MJ • 800 MJ • 560 MJ

28. A gasoline engine with an efficiency of 30% operates between a high temperature T1 and a low temperature T2 = 320 K. If this engine operates with Carnot efficiency, what is the high-side temperature T1 ? • 1066 K • 868 K • 614 K • 457 K

29. A Florida home is kept cool in the summer by an air conditioner. The outside temperature is 36°C and the inside of the home is kept at 18°C. If 50 MJ of heat is removed from the house per hour, what is the minimum power that must be provided to run the air conditioner? • 214 W • 430 W • 860 W • 1720 W

30. The surface of the sun is approximately 5700 K and the temperature of the Earth's surface is about 290 K. What total entropy change occurs when 1000 J of heat energy is transferred from the sun to the Earth? • 2.89 J/K • 3.27 J/K • 3.62 J/K • 3.97 J/K

31. The efficiency of a Carnot engine operating between 100°C and 0°C is most nearly • 7% • 15% • 27% • 51%

32. What is the coefficient of performance of a refrigerator that operates with Carnot efficiency between temperatures -7°C and +31°C? • 7.0 • 9.1 • 10.0 • 13.2

33. How much work is required, using an ideal Carnot refrigerator, to remove 1 J of heat energy from helium gas at 4 K and reject this heat to a room temperature (293 K) environment? • 13.9 J • 26.7 J • 52.6 J • 72.3 J

34. On a cold day, a heat pump is used to extract heat energy from the outside air at -5°C and bring it into the +20°C house. What minimum amount of work must be done to bring 1000 J of heat energy into the house? • 40.0 J • 60.0 J • 85.3 J • 100.1 J

35. Suppose a power plant uses a Carnot engine to generate electricity, using the atmosphere at 300 K as the low temperature reservoir. Suppose the power plant produces 1 x 106 J of electricity with the hot reservoir at 500° K during one day and then produces 1 x 106 J of electricity with the hot reservoir at 600° K during the second day. On these two days the thermal pollution was • greatest on the first day • greatest on the second day • the same on both days • zero on both days

36. A bottle containing an ideal gas has a volume of 2m3 and a pressure of 1 x 105 N/m2 at a temperature of 300° K. The bottle is placed against a metal block that is maintained at 900° K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900° K. The change in internal energy of the gas is +6 x 105 J. How much heat did the gas absorb? • 0 • 4 x 105 J • 6 x 105 J • 10 x 105 J

37. A bottle containing an ideal gas has a volume of 2m3 and a pressure of 1 x 105 N/m2 at a temperature of 300° K. The bottle is placed against a metal block that is maintained at 900° K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900° K. The change in internal energy of the gas is 6 x 10 5 J. What is the change in entropy of the block? • 0 • +670 J/K • -440 J/K • -1100 J/K

38. When gasoline is burned, it gives off 46,000 J/gram of heat energy. If an automobile uses 13.0 kg of gasoline per hour with an efficiency of 21%, what is the average horsepower output of the engine? (1 HP = 746 W) • 46.76 HP • 108.7 HP • 67.2 HP • 33.6 HP

39. An ideal gas at pressure, volume, and temperature, P0 , V0 , and T0 , respectively, is heated to point A, allowed to expand to point B at constant temperature 2T0 , and then returned to the original condition. The internal energy increases by 3P0V0 /2 going from point B to point T0 . In going around this cycle once, which quantity equals zero? • The total change in internal energy of the gas. • The total work done by the gas. • The total heat added to the gas. • All three are zero.

40. An ideal gas at pressure, volume, and temperature, P0 , V0 , and T0 , respectively, is heated to point A, allowed to expand to point B at constant temperature 2T0 , and then returned to the original condition. The internal energy increases by 3P0V0 /2 going from point B to point T0 . How much heat left the gas from point B to point T0 ? • 0 • POVO/2 • 3 POVO/2 • 5 POVO/2

41. For which system is heat usually transferred from the cooler part of the system to warmer material? • a stove as it heats up water • a refrigerator that is running • an electric fan that is running • none of these, because it is impossible to transfer heat in this manner

42. An ideal gas at pressure, volume, and temperature, P0 , V0 , and T0 , respectively, is heated to point A, allowed to expand to point B at constant temperature 2T0 , and then returned to the original condition. The internal energy increases by 3P0V0 /2 going from point B to point T0 . How much heat left the gas from point T0 to point A? • 0 • POVO/2 • 3 POVO/2 • 5 POVO/2

43. Heat is applied to an ice-water mixture to melt the ice. In this process • work is done by the ice-water mixture. • the temperature increases. • the internal energy increases. • all of these will occur.

44. What is the work done by the gas as it expands from pressure P1 and volume V1 to pressure P2 and volume V2 along the indicated straight line? • (P1 + P2) (V2 – V1) /2 • (P1 + P2) (V2 – V1) • (P1 - P2) (V2 – V1) /2 • (P1 - P2) (V2 + V1)

45. As the ideal gas expands from pressure P1 and volume V1 to pressure P2 and volume V2 along the indicated straight line, it is possible that • the temperature stays constant. • the internal energy decreases. • the gas is changing state. • all of these are impossible for this particular graph.

46. Which of the following increases the internal energy of a solid metal rod? • Raising it to a greater height. • Throwing it through the air. • Having the rod conduct heat. • Having the rod absorb heat.

47. An electrical generating plant operates at a boiler temperature of 220°C and exhausts the unused heat into a nearby river at 19°C. If the generating plant has a power output of 800 megawatts and if the actual efficiency is 3/4ths the theoretical efficiency, how much heat per second must be delivered to the boiler? (0°C = 273 K) • 5200 megawatts • 1810 megawatts • 3620 megawatts • 2600 megawatts

48. During each cycle of operation a refrigerator absorbs 55 cal from the freezer compartment and expels 85 cal to the room. How much work input is required to operate the system? (1 cal = 4.186 J) • 125 J • 146 J • 356 J • 565 J

49. During each cycle of operation a refrigerator absorbs 55 cal from the freezer compartment and expels 85 cal to the room. If one cycle occurs every 10 s, how many minutes will it take to freeze 500 gm of water, initially at 0°C? (Lv = 80 cal/gm) • 800 min • 4400 min • 121 min • 60 min

50. An electrical generating plant operates at a boiler temperature of 220°C and exhausts the unused heat into a nearby river at 18°C. What is the maximum theoretical efficiency of the plant? (0°C = 273 K) • 61% • 32% • 21% • 41%