Question

A water pump raises 50 litre of water through a
height of 25 m in 5 s. Calculate the power of the
pump required.
(Take g = 10 N kg-' and density of water
= 1000 kg m-3).
​

Answer 1

Answer:2500w

Explanation: 1l=1kg ⇒ 50l=50kg

mass,m=50kg    acceleration due to gravity,g=10N/kg    distance,s=25m=h

t=5s

Force,F=m×g

            = 50kg × 10N/kg

            = 500N

Work,W=F×s

            =500N×25m

            =12,500Nm

            =12,500J

                                          OR

Work,W=mgh

            =50kg×10N/kg×25m

            =12,500J

Power,P=W/t

             =12,500/5

             =2500J/s

             =2500w

Answer 2

Height = 25m

Time = 5s

Volume = 50l

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

density = mass / volume

So,

${ \blue{ \bf{ 1m² = 1000l }}}$

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

1000=mass/(1/1000×50)

mass=1000×50×1/1000

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

${ \blue{ \bf{W=F=mg=50×10=500 }}}$

P=500×25/5

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