An engine pumps water through a hose pipe water passes through the pipe and leaves it with velocity of 2 m/s. The mass per unit length of water in the pipe is 100 kg/m .What is the power of the engine ?

Options

A. 400 W
B. 200 W
C. 100 W
D. 800 W

Answer

A

Explanation

The mass of water flow in one second from the pipe ` = m/t`
` :. M = m/l xxl/t`
= mass per unit `xx ` velocity
` :. M = m/l v`
Power means kinetic energy of flowing water ,
` :. "Power " P = 1/2 Mv^(2)`
` = 1/2 ((mv)/l)v^(2)`
`= 1/2 .(mv^(3))/l `
` = 1/2 xx100 xx(2)^(3)`
` [ :. m/l = 100 "kg/m"]`
= 400 W