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# D a harmonic wave and a pulse propagating on the same

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D) A harmonic wave and a pulse propagating on the same string should have the same wave speed, as long as the disturbances they produce are sufficiently small. 17) 18) A wave on a stretched string is described by y = 0.02 sin (32t - 16x), where the coefficients are given in SI units. What is the wave speed? A) 0.64 m/s B) 0.5 m/s C) 0.32 m/s D) 2 m/s 18) 19) Consider the equation Q = D U + W. Which of the following statements is WRONG? A) W is negative when the work is done on the system, and not by the system. B) When kinetic and potential energy (K and E p ) of the system change, the equation should be expanded as: Q = D U + W-( D K+ D E p ) C) To say that Q is positive in some process is the same as saying that a net positive amount of energy is transferred to the system due to temperature difference alone. D) If a systems goes from state 1 to state 2 in two different quasi-static processes, D U is the same, whereas Q is likely to be different. 19) A-3

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20) Which of the following statements is WRONG? A) If one shakes a thermally insulated jar of water, the process can be described by the equation D U = W, where U is the internal energy of the water and W is the work done by the water. B) A process of isobaric expansion of a gas can be descibed by equation D U=Q. C) The average kinetic energy associated with each degree of freedom of a molecule is 1/2kT. D) A quasi-static process, which begins and ends at the same pressure, is not necessarily isobaric. 20) 21) A compression, at a constant pressure of 110 kPa, is performed on 4.0 moles of an ideal monatomic gas (C v = 3/2 R). The compression reduces the volume of the gas from 0.5 m 3 to 0.24 m 3 . The change in the internal energy of the gas, in kJ, is closest to: A) -42 B) 72 C) -72 D) 42 21) 22) Which of the following is a WRONG statement? A) The coefficient of performance of a Carnot refrigerator goes to infinity as the temperature of the cold reservoir approaches the temperature of the hot reservoir. B) Quality of energy provided by sunlight is about the same as quality of energy supplied by a heat reservoir with the temperature of the outer shell of the Sun. C) A Carnot refrigirator uses work W (usually supplied to it as electricity) to make its interior to reject heat Q to the outside world, where W is always less than Q. D) For a Carnot engine, the work it performs is always less than the amount of heat obtained from the hot reservoir. 22) 23) Which of the following is a WRONG statement? A) Heat can be transferred from a colder to a hotter object as a part of a complex thermodynamic process. B) Decreasing entropy corresponds to increasing order in the system. C) The amount of work produced by a heat engine within one Carnot cycle can vary, even if the temperatures of the hot and cold reservoirs as well as the amount of heat the engine rejects to the cold reservoir are all given. D) In the Carnot cycle of a heat engine, the net work done in one cycle is the sum of works during isothermal expansion and isothermal contraction. 23) 24) A heat pump with a COP of 4.7 delivers to a house heat at a rate of 14 kW. At what rate is it doing work? A) 66 kW B) 3.1 kW C) 80 kW D) 2.5 kW 24) A-4
Answer Key Testname: FINAL AS 1) C 2) D 3) C 4) C 5) C 6) A 7) A 8) C 9) A 10) D 11) A 12) C 13) B 14) D 15) C 16) C 17) C 18) D 19) B 20) A 21) A 22) C 23) C 24) D A-5
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D A harmonic wave and a pulse propagating on the same...

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