Question

A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m³ in 15 min. If the tank is 40 m above the ground, and the efficiency of the pump is 30%, how much electric power is consumed by the pump?

Answer 1

Volume of the tank, V = 30 m³

Time of operation, t = 15 min = 15 × 60 = 900 s

Height of the tank, h = 40 m

Efficiency of the pump, = 30%

Density of water, ρ = 10³ kg/m³

Mass of water, m = ρV = 30 × 10³ kg

Output power can be obtained as:

For input power P_i,, efficiency is given by the relation: