Question

What power is needed to fill an overhead tank of capacity 50000 lit in two hours, if the water is to be lifted through a height of 30m?

Answer 1

Explanation:

Power = energy /time.

a pump can raise 1000 litres of water per minute.

hence, in 1 min, 1000 litres of water raise. so, in 1 min, mass of water raise = density of water x volume = 1000 kg/m³ x 1000 × 10^-3 m³ 3

= 1000 Kg

mass raise per minute of water = 1000

Kg now, potential energy of 1000 kg of water at height 45 m = mgh of water = 4.5 x 105/60sec [ because 1min = : 60 sec, raise water at the height = 45

= 1000 × 10 × 45 = 450000 J = 4.5 × 105 J So, energy of water per second = power

m] : 7500 W =

Now, we know, 1 horse power = 746 W so, 7500 W power = 7500/746 Hp = 10.05 Hp