Question

A pump on a ground floor of a building can pump up water to fill a tank of volume 30m square in 15 min .if the tank is 40m above the ground ,and the efficiency of pump is 30%,how much electric power is consumed by the pump?

Answer 1

Mass of water = density * volume = 30 *1000 = 30000kg
Work done= mgh= 30000*10*40 = 12000000 J
Pump only 30% efficient, so
30/100 * Work by pump = 12000000 J
Work by pump = 4x10⁷ J
electric power is consumed by the pump= Work by pump / time = 4.4x10⁴ Watt