Which of these is irreversible?

  1. an ideal Carnot cycle
  2. heat flowing from a hot body to a cold one
  3. a very slow, frictionless compression of a gas
  4. a quasi-static isothermal expansion
Answer

B) heat flowing from a hot body to a cold one

Heat never flows back by itself. SLO P-11-C-14 · Understanding

Physics MCQ · More Heat Engines, Second Law and Entropy MCQs · Practise