Answer:
Explanation:
Be careful how you answer this. Heat is not a useful by product of work. It does not add to the efficiency of an engine.
The actual work done by the engine is 45 J - 31 J = 14 J
The efficiency is = Useful Work / Total Work in * 100%
Useful Work = 14 J
Total Work = 45 J
Efficiency = (14/45) * 100
Efficiency = 31.1 % efficient.