A pulley system operates with 40% efficiency. if the work put in is 200 joules, how much useful work is produced?

1. Efficiency is the measure of how efficient a process is. It is used to assess the ability of a process in avoiding waste energy, materials, money and time in doing a desirable output. It is calculated as;

Efficiency = useful energy ouput / total energy input

.40 = useful work / 200

useful work = 80 joules