A hose pipe has a diameter of `2.5 cm` and is required to direct a jet of water to a height of atleast `40 cm`. Find the minimum power of the pump needed for this hose.

Options

A. `21.5 J`
B. `21.5 KJ`
C. `10.5 KJ`
D. `10.5 J`

Answer

`(2)`

Explanation

Volume of water ejected per sec
`Av = pi((d)/(2))^(2) xx sqrt(2gh) rho Kg/s`
Kinetic energy of water leaving hose/ sec
`K.E = 1/2 mv^(2) =1/8 pi d^(2) xx(2gh)^(3/2) xx rho`
`= 1/8 xx 3.14 xx(2.5 xx 10^(-2))^(2) xx `
`(2 xx 9.8 xx 40)^(3/2) xx 1000`
`= 21.5 KJ`