Question

Why is it impossible for a heat engine to be 100% efficient?
a. Entropy always decreases in a heat engine
b. Work cannot be done on a heat engine
c. Some heat is always lost to the environment
d. Heat is constantly being created

Answer 1

c. Some heat is always lost to the environment.

This is known as heat loss or waste heat, and it is usually due to factors such as friction, radiation, and conduction. These losses result in a decrease in the overall efficiency of the heat engine. Even with advanced engineering and technology, it is not possible to completely eliminate these heat losses, making it impossible for a heat engine to be 100% efficient.