國中教甄｜理化理化102 年第 29 題單選題

A heat engine operates between 200 K and 100 K. In each cycle it takes 100 J from the hot reservoir, loses 25 J to the cold reservoir and does 75 J of work. This heat engine violates:

Aboth the first and second laws of thermodynamics

Bthe first law but not the second law of thermodynamics

Cthe second law but not the first law of thermodynamics正確答案

Dneither the first law no the second law of thermodynamics

答案與詳解

正確答案

Q_H = W + Q_C（100 = 75 + 25），能量守恆，符合第一定律；但效率 75/100 = 75% 超過卡諾效率 1 − 100/200 = 50%，違反第二定律。

Aboth the first and second laws of thermodynamics✕ 錯誤

100 J = 75 J + 25 J，能量守恆，沒有違反第一定律。

Bthe first law but not the second law of thermodynamics✕ 易錯陷阱

剛好說反：本熱機符合第一定律，違反的是第二定律。

Cthe second law but not the first law of thermodynamics✓ 正確

Dneither the first law no the second law of thermodynamics✕ 易錯陷阱

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