A proposed heat engine operates between a hot reservoir at 600 K and a cold reservoir…
PHYSICS · Single correct · AP · Physics 2: Algebra-based · Thermodynamics · Thermodynamics
Problem
A proposed heat engine operates between a hot reservoir at 600 K and a cold reservoir at 300 K. During each cycle it absorbs 300 J of heat from the hot reservoir, does 240 J of mechanical work, and expels 60 J of heat to the cold reservoir. Determine whether the device is consistent with the second law of thermodynamics.
(a) Yes, because the energy balance for each cycle is satisfied.
(b) No, because the total entropy change for one cycle is negative.
(c) Yes, because its efficiency of 80% is less than 100%.
(d) Yes, because the total entropy change for one cycle is positive.