An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of `2 ms^(1)`. The mass per unit length of water in the pipe is `100 kgm^(-1)`. What is the power of the engine?

Options

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

Answer

A

Explanation

`P=Fv=mav= rhoV(v^2)/t=(rhoAlv^2)/(t)=rhoAv^3`
Mass per unit length `=m/l=(rhoV)/l=rhoA`
`:. P = (100)(2)^3 = 800W.`