$($Question $1)$

Given that the pipe in Figure $1$ is $600m$ long and $400mm$ in diameter, that water is initially flowing through it at $100\frac{L}{s},$ and the pressure waves travel along with it at $1200\frac{m}{s}.$ Water density $=1000K\frac{g}{m^3}.$

Determine the maximum water hammer pressure at the valve $($at $N)$ and at point $250m$ from the reservoir,

$($a$)$ If the valve is partially closed in $2$ seconds, reduce the flow from $100\frac{L}{s}$ to $25\frac{L}{s}.$

$($b$)$If the valve is completely closed in $0\mathrm{.}8$ seconds.