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Thermodynamics: An Engineering Approach, 4/e

Yunus A. Çengel, University of Nevada, Reno
Michael A. Boles, North Carolina State University

The Second Law of Thermodynamics

Multiple Choice Quiz


1	A heat engine has a thermal efficiency of 45%. How much power does the engine produce when heat is transferred into it at a rate of 10⁹ kJ/Hr?
		A)	50 MW
		B)	75 MW
		C)	100 MW
		D)	125 MW


2	A refrigerator has a coefficient of performance of 1.6. How much work must be supplied to this refrigerator for it to reject 1000 kJ of heat?
		A)	385 kJ
		B)	627 kJ
		C)	836 kJ
		D)	1000 kJ


3	The thermodynamic efficiency of a heat engine that rejects heat at a rate of 20 MW when heat is supplied to it at a rate of 60 MW is:
		A)	33.3%
		B)	50%
		C)	66.7%
		D)	75%


4	A Carnot engine operates using a 527 °C energy reservoir and a 27 °C energy reservoir. The thermodynamic efficiency of this engine is:
		A)	50%
		B)	62.5%
		C)	73.6%
		D)	103%


5	A Carnot heat pump uses thermal reservoirs at -27 °C and 57 °C. How much power does this pump consume to produce a 100 kW heating effect?
		A)	9.1 kW
		B)	12.7 kW
		C)	15.3 kW
		D)	20.7 kW


6	An inventor claims to have created a heat engine which produces 10 kW of power for a 15 kW heat input while operating between energy reservoirs at 27 °C and 427 °C. Is this claim valid?
		A)	Yes
		B)	No


7	A manufacturer claims that its refrigerator has a COP of 1.4 when cooling food at 7 °C using ambient air at 23 °C as a heat sink. Is this claim valid?
		A)	Yes
		B)	No


8	A heat engine whose thermodynamic efficiency is greater then that of a Carnot device using the same energy reservoir is known as:
		A)	A perpetual machine of the zeroth kind
		B)	A perpetual machine of the first kind
		C)	A perpetual machine of the second kind
		D)	A perpetual machine of the third kind


9	According to Clausius, heat will transfer naturally from cold bodies to hot bodies.
		A)	True
		B)	False


10	Which of the reversible processes listed below are used to form a Carnot cycle?
		A)	Isometric, isobaric
		B)	Isometric, adiabatic
		C)	Isobaric, adiabatic
		D)	Isothermal, adiabatic

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