Why is it impossible for a thermal cycle to operate at 100% efficiency?

Mechanical Engineering Mcqs for PPSC, FPSC, NTS, and Pakistan government job tests. Select an option below, then read the explanation.

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Subject
Mechanical Engineering Mcqsmechanical-engineering-mcqs
Published
29 Jan 2019
Last updated
28 May 2026

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Explanation

Achieving complete efficiency in a thermal cycle is unattainable because it requires reaching absolute zero temperature (0 K), which is physically impossible. Other factors like friction, leakage, or imperfect substances contribute to inefficiencies but the fundamental limitation is the unattainability of absolute zero.

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