Exam-style question
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Why is no heat engine perfectly efficient?.
- A.Some energy is always lost as waste heat
- B.All energy is converted to work
- C.Heat engines operate at constant temperature
- D.They do not follow the laws of thermodynamics
Model answer
What a good answer should say
- Some energy is always lost as waste heat
Explanation
Why this works
According to the Second Law of Thermodynamics, some energy is inevitably lost as waste heat in any heat engine, preventing perfect efficiency.
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