Question

The power of an engine that lifts 10^5 kg of coal per hour from a mine of 360 m deep is

Answer 1

Height (h) = 360m
Acceleration due to gravity = 10 m/s^2
Time(t) = 1 hour = 3600 s
Then,
P.E = mgh
      = 10^5 * 10 * 360 J
Work done = P.E = 10^5 * 10 * 360 J

We know,
Power = Work done / Time
            = 10^5 x 10 x 360/3600
            = 10^5 watt.