Question

If a heat engine does 672 J of work from a heat reservoir of 1,600 J, then what is the efficiency of the
heat engine?
answers:
42%

92%

58%

38%

Answers

GPT-4o mini
The efficiency (\( \eta \)) of a heat engine is calculated using the formula:

\[
\eta = \frac{W}{Q_h}
\]

where \( W \) is the work done by the engine and \( Q_h \) is the heat extracted from the hot reservoir.

Given:
- Work done (\( W \)) = 672 J
- Heat from the reservoir (\( Q_h \)) = 1,600 J

Now, we can substitute the values:

\[
\eta = \frac{672 \, \text{J}}{1,600 \, \text{J}}
\]

Calculating this gives:

\[
\eta = 0.42
\]

To express this as a percentage, we multiply by 100:

\[
\eta = 0.42 \times 100 = 42\%
\]

Thus, the efficiency of the heat engine is **42%**.