A farmer uses 3450 J of energy on a wheel and axle to lift a 15 kg bucket of water 20 m to the top of her well. What is the efficiency of the system?

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

Efficiency = 15 (9.81) (20) / 3450 = 0.85