Question $4.$ Water $($kinematic viscosity $=1\mathrm{.}139*10^6$ m$2/$s$)$ is flowing through $25-$metre long pipe having a diameter of $10$ cm$.$ The pipe is made of galvanized iron $($e $=0\mathrm{.}15$ mm$).$ The head loss is $7\mathrm{.}5$ cm$.$ Calculate the flow rate through the pipe