Question

A pump raises 50 litre of water through a height of 25 m in 5 s. Calculate the power of the pump required.

Answer 1

Power = work done/ time

mass of water = 50kg as density of water is 1 kg/litre or 1g/ml

now in this case work done = change in potential energy

work done = mgh - 0

= 50 * 10 *25 J = 12500 J

power = 2500 W

Answer 2

Height = 25m

Time = 5s

Volume = 50l

${ \red{ \bf{ Let's \: convert \: volume \:to \:density: }}}$

density = mass / volume

So,

${ \red{ \bf{ 1m² = 1000l }}}$

${ \red{ \bf{ density = mass / volume }}}$

1000=mass/(1/1000×50)

mass=1000×50×1/1000

${ \red{ \bf{ =50kg }}}$

${ \red{ \bf{W=F=mg=50×10=500 }}}$

P=500×25/5

${ \red{ \bf{P=2500W \: Ans }}}$