Thermodynamics 2

Thermodynamics 2 1. The temperature of a body is 50 deg F. Find its temperature in deg C. A. 147.6 B. 10 C. 45.6 D. 32 2. How many calories are required to raise 20 kg of copper ( c p = 0.208 BTU/lbm-deg F) from 80 deg C to 600 deg C? A. 2.163 x 10 positive 6 cal B. 0.216 x 10 positive 6 cal C. 0.163 x 10 positive 6 cal D. 1.631 x 10 positive 6 cal 3. 2 lbm of 200 deg F iron (cp = 0.1 BTU/lbm-deg F) are dropped into a gallon of 40 deg F water. What is the final temperature of the mixture in deg F? A. 55.21 B. 48.12 C. 38.92 D. 43.74 4. In a laboratory experiment, 50 grams of copper is heated by a steam at 100 deg C, is dropped into a 50 g aluminum calorimeter containing 100 grams of water at 27 deg C. If the final temperature of the mixture is 30 deg C, find the specific heat of the copper (caluminum = 0.22 cal/g-C deg) A. 0.095 cal/g-C deg B. 0.077 cal/g-C deg C. 0.99 cal/g-C deg D. 0.66 cal/g-C deg 5. Heat is supplied to 20 lbm of ice (c p = 0.5 BTU/lbm-deg F) at 0 deg F at the rate of 160 BTU/sec. How long will it take to convert the ice to steam (cp = 0.5 BTU/lbm-deg F) at 213 deg F? A. 153.78 sec B. 163.78 sec C. 173.76 sec D. 143.78 sec 6. What happen when there is a transition from liquid state to solid state loss of? A. energy B. molecules C. heat of fusion D. elements devilbat

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Thermodynamics 2 7. Two liquids enter a mixing chamber and are discharged at 80 deg F at the rate of 50 gal/min. Liquid A enters at 140 deg F with a specific heat of 10 BTU/gal-deg F. Liquid B enters at 65 deg F with a specific heat of 8.33 BTU/gal-deg F. What is the specific heat of the mixture? A. 4.12 BTU/gal-deg F B. 8.62 BTU/gal-deg F C. 5.32 BTU/gal-deg F D. 6.02 Btu/gal-deg F 8. A lead bullet of mass M passed a tree trunk and emerges on the other side. The speed of the bullet is 300 m/sec as it enters and 80 m/sec as it emerges, assuming that 60% of the loss of kinetic energy is stored as heating the bullet, calculate the rise in temperature of the bullet. Specific heat of lead is 0.03 cal/g-deg C. A. 199.71 deg C B. 180 deg C C. 200 deg C D. 194 deg C 9. A 5 gram bullet is propelled by a powder charge producing 500 calories of usable energy. What is the bullet muzzle velocity? A. 910 m/s B. 915 m/s C. 920 m/s D. 930 m/s 10. A nonflow (closed) system contains 1 lb of an ideal gas (c p = 0.24, cv = 0.17). The gas temperature is increased by 10 deg F while 5 BTU of work done by the gas. What is heat transfer in BTU? A. 6.7 B. -6.7 C. 7.6 D. -7.6 11. Air at 27 deg C is heated to 927 deg C. Find the change in enthalpy, heating air as a perfect gas. A. 704.2 kJ/kg B. 904.2 kJ/kg C. 804.2 kJ/kg D. 604.2 kJ/kg

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Thermodynamics 2

12. Relationship constant volume. A. Dalton’s law B. Charles’ law C. Boyle’s law D. Henry’s law 13. A. B. C. D.

between

temperature

and

pressure

at

Which of the following is Charles’ law? V/T = k V = k x 1/P PV = mRT P1/T1 = P2/T2

14. A quantity of gas occupies 1.2 cu. ft at STP. The gas is allowed to expand to 1.5 cu. ft and at 15 psia. What is the new temperature? A. 700 deg R B. 627.6 deg R C. 640 deg R D. 590 deg R 15. A certain gas occupies a volume of 6 liters under pressure of 720 mmHg at 25 deg C. What volume in liter will this occupy under STP condition of temperature and the pressure? A. 5.2 B. 2.5 C. 4.5 D. 5.4 16. A 1 cu. m tank is filled with gas at room temperature 20 deg C and pressure of 100 kPa. How much is there if the gas is air with R = 0.287? A. 1.189 B. 1.201 C. 0.099 D. 17.422 17. A kilomile of Methane is 16 kg. Compute the density of Methane at 20 deg C and 5 atm pressure. A. 3.33 kg/cu. m B. 2.66 kg/cu. m C. 6.02 kg/cu. m D. 4.80 kg/cu. m devilbat

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Thermodynamics 2

18. A group of 30 IIEE regular member attend a meeting in aroom which is 20 ft wide, 16 ft long and a ceiling height of 8 ft. The room is completely sealed off and insulated. Each person gives off 140 kcal/hr of heat and occupies a volume of 0.2 cu. m. The room has an air initially at 105 kPaa pressure and temperature of 18 deg C. Calculate the room temperature after 1 minute. A. 23 deg C B. 25 deg C C. 27 degC D. 29 deg C 19. An insulated constant volume system containing 1.36 kg of air receives 53 kJ of paddle work. If the initial temperature is 27 deg C, what is the final temperature? A. 354 B. 380 C. 344 D. 360 20. A piston-cylinder system contains a gas which expands under a constant pressure of 1200 lbf/sq. ft. If the piston is displaced 12 inches during the process, and the piston diameter is 24 inches, what is the work done by the gas on the piston? A. 3768 ft-lbf B. 1234 ft-lbf C. 7894 ft-lbf D. 6587 ft-lbf 21. How many BTU,s are needed to isothermally compress 4 lbm mass of 240 deg F air twice the original pressure A. -132.93 B. -321.93 C. -244.94 D. -200.93 22. How does an adiabatic process compare to an isentropic process? A. adiabatic: heat transfer = 0: isentropic: heat transfer is not equal to 0 B. adiabatic: heat transfer is not equal to 0: isentropic: heat transfer = 0 C. adiabatic: reversible: isentropic: not reversible D. adiabatic: heat transfer = 0: isentropic: reversible devilbat

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Thermodynamics 2

23. In an adiabatic isentropic process, P1 = 200 psi, P2 = 300 psi, and T1 = 700 deg R. Find T2 using k = 1.4. A. 786 deg R B. 680 deg R C. 576 deg R D. 590 deg R 24. The entrance enthalpy, velocity and height of a 5 lbm/sec system are 1000 BTU/lbm, 100 ft/sec, and 100 feet respectively. 50 BTU/sec are lost to the surroundings. The exit enthalpy, velocity, and height are 1020 BTU/lbm, 50 ft/sec, and 0 feet respectively. What is the input horsepower? A. 210.8 B. 250 C. 280 D. 234.45 25. No heat can be produced without any losses of heat. This is one of the useful statements of the second law of thermodynamics. A. Partly true B. True C. Partly false D. False 26. The maximum thermal efficiency that can be obtained in an ideal reversible heat engine operating between 1540 deg F and 340 deg F is closest to ________ %. A. B. C. D.

55 58 60 62

27. A Carnot cycle heat engine operates 1540 deg F and 40 deg F and rejects 250 BTU/lb to the low temperature reservoir of heat sink. Maximum entropy change in BTU/lb-deg R of the working fluid for any process in the cycle is: A. 0.78 B. 0.50 C. 0.89 D. 0.92 devilbat

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Thermodynamics 2

28. Second law limitation on the maximum horsepower output from any power unit burning 1,000,000 BTU/hr of fuel with high and low temperature extremes of 154 deg F and 40 deg F is: A. 255 B. 256 C. 295 D. 300 29. A Carnot machine operates between the hot reservoir at 200 deg C and a cold reservoir at 20 deg C. When operated as an engine it receives 1000 kJ/kg, find the work output. A. B. C. D.

381 440 390 400

kJ/kg kJ/kg kJ/kg kJ/kg

30. A Carnot machine operates between the hot reservoir at 200 deg C and a cold reservoir at 20 deg C. When operated as an engine it receives 1000 kJ/kg. Find the coefficient of performance (COP) when used as refrigerator. A. 1.77 B. 1.99 C. 2.63 D. 1.63

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