## 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? | Learn NCERT solution | Education portal Class 11 Physics | Study online Unit-6 Work, Energy And Power

### Q.15:- 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?

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, η = 30 %
Density of water, ρ = 103 kg/m3
Mass of water, m = ρV = 30 × 103 kg
Output power can be obtained as:
P0 = Work done / Time  = mgh / t
= 30 × 103 × 9.8 × 40 / 900  =  13.067 × 103 W
For input power Pi,, efficiency η, is given by the relation:
η = P0 / Pi  =  30%
Pi = 13.067 × 100 × 103  / 30
= 0.436 × 105 W  =  43.6 kW