Physics
Physics
Problem
A cyclic engine interacts with three thermal reservoirs in one cycle as follows: it absorbs 150 J of energy as heat from a reservoir at 600 K, absorbs 50 J as heat from a reservoir at 300 K, rejects 180 J of energy as heat to a reservoir at 400 K, and delivers 20 J of work. Using numerical entropy calculations, evaluate whether this cycle can occur, and justify your conclusion in no more than three sentences.Intuitive explanation
The key is checking the second law of thermodynamics: a real cycle is only possible if the total entropy change of the universe is non-negative. Calculate the entropy change for each reservoir (using ), sum them, and see if the result is —if it's negative, the cycle violates the second law and cannot occur. This test tells you whether the proposed process respects fundamental physical limits.
Intuitive explanation
The key is checking the second law of thermodynamics: a real cycle is only possible if the total entropy change of the universe is non-negative. Calculate the entropy change for each reservoir (using ), sum them, and see if the result is —if it's negative, the cycle violates the second law and cannot occur. This test tells you whether the proposed process respects fundamental physical limits.