To determine the efficiency of an engine, we use the formula:
[tex]\[ e = \frac{W_{\text{done}}}{Q_{\text{in}}} \][/tex]
where:
- [tex]\( W_{\text{done}} \)[/tex] is the work done by the engine,
- [tex]\( Q_{\text{in}} \)[/tex] is the heat energy taken in by the engine.
Given:
- [tex]\( W_{\text{done}} \)[/tex] = 576 J,
- [tex]\( Q_{\text{in}} \)[/tex] = 720 J.
Now, plug these values into the formula:
[tex]\[ e = \frac{576}{720} \][/tex]
This simplifies to:
[tex]\[ e = 0.8 \][/tex]
To convert this efficiency to a percentage, we multiply by 100:
[tex]\[ e \times 100 = 0.8 \times 100 = 80\% \][/tex]
Therefore, the efficiency of the engine is:
[tex]\[ \boxed{80\%} \][/tex]
So, the correct answer is:
D. [tex]\( 80\% \)[/tex]
