SAT Subject Physics Practice Question 136: Answer and Explanation

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Question: 136

9. During each cycle, a heat engine absorbs 400 J of heat from its high-temperature source and discards 300 J of heat into its low-temperature sink. What is the efficiency of this engine?

A.
B.
C.
D.
E.

Correct Answer: B

Explanation:

Since the engine takes in 400 J of energy and produces only 400 J – 300 J = 100 J of useful work, its efficiency is .

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