Question

An engine exhausts 1140 j of energy for every 3790 j of energy it takes in. what is its efficiency?

Answer 1

$Given:\\ Q_+=3790J\\Q_-=1140J\\\\Find:\\\eta=?\\\\Solution:\\\\\eta=1- \frac{Q_-}{Q_+} \\\\\eta=1- \frac{1140J}{3790J} \approx 0.7$