What should be the power of an engine required to lift 90 metric tonnes of coal per hour from a mine whose depth is 200m?

Explanation

Here, mass of the coal to be lifted, `m = 90` metric tonnes
`=90xx1000kg = 9xx10^4kg`
height through which the coal is to be lifted, `h = 200m`
time during which the coal is to be lifted, `t =1 h =60xx60 = 3600s`
work done to lift the coal, i.e., `W = mgh = (9xx10^4kg)(10m//s^2)(200m) =18xx10^7J`
Power of the enine requred, i.e.,`P =(W)/(t) = (18xx10^7J)/(3600s) = 50000 W = 50kW`