Question

A heat engine produces 30, 000 J of mechanical work per second of operation. If its efficiency is 20% how much heat is discharged from this engine per second?  

Answer 1

$\eta=1-\frac{Q_2}{Q_1}\implies$

$Q_2=(1-\eta)Q_1,$

$Q_2=(1-0.2)\cdot 30000=24000~J.$