What is the power of an engine which can lift 20 metric tons of coal per hour from a 20 m deep mine?

Given,
Mass, m = 20 metric tons = 20 x 1000 kg
Distance, s = 20m,
Time, t = 1 hour = 3600s
The capacity to do work is termed as Energy and the Energy expended to do work in unit time is termed as Power.
We have, Power,
$\mathrm{P}=\frac{\mathrm{Energy} \mathrm{consumed}}{\mathrm{time}}$
Power =$\frac{\mathrm{mg}\times \mathrm{s}}{\mathrm{t}}$                 (Here energy possessed is potential energy)
Power =$\frac{20\times 1000\times 9.8\times 20}{3600}$
Power = 1.09 x 10³ watts
Hence, the Power of an engine is 1.09 x 10³ watts.