Question

In each cycle, a heat engine an input of 1940 J of heat and exhausts 1480 J of heat. What is the thermal efficiency?

Answer 1

Answer:

0.237 (23.7 %)

Explanation:

The thermal efficiency of an engine is given by:

$\eta=\frac{W}{Q_{in}}$

where

W is the useful work output of the engine

$Q_{in}$ is the heat in input

Here we have:

$Q_{in}=1940 J$

and the work done is the total heat in input minus the heat exhausted:

$W=1940 J - 1480 J=460 J$

So, the efficiency is

$\eta=\frac{460 J}{1940 J}=0.237$ (23.7 %)