A pump motor is used to deliver water at a certain rate from a given pipe. To obtain twice as much water from the same pipe in the same time, power of the motor has to be increased to :

Options

A. 16 time
B. 4 times
C. 8 times
D. 2 times

Answer

c

Explanation

Here, W=K.E. of water
`:.` Power `P=W/t=(1/2mv^2)/(t)=(mv^2)/(2t)`
Work done in second case when mass of water is doubled `W.=1/2(2m)v^2`
Power `P.=(mv^2)/(t)`
`:. P/P=(mv^2)/(t)xx(2t)/(mv^2)=2`
P.=2P.