Question

The diagram shows a heat engine.

An illustration with a red block on the left labeled Q Subscript h Baseline with a blue block on the right labeled Q Subscript c Baseline. There is an arrow from the blue block into the red block.

In which area of the diagram is unusable thermal energy detected?
W
X
Y
Z

Answer 1

D

Step-by-step explanation:

Answer 2

Based on the image attached, the unusable thermal energy is detected in the area of option d: Z.

Heat engines work by transferring heat from a hot reservoir to a cold reservoir, and converting some of that heat into work.

However, the second law of thermodynamics states that no heat engine can be perfectly efficient, and some of the heat must be rejected to the cold reservoir.

Note that the other areas of the diagram represent:

W: Work produced by the heat engine.

X: Heat engine itself.

Y: Heat transferred from the hot reservoir to the heat engine.

Therefore, the answer is Z, which is the cold region/reservoir.