$1$ A circular pipe $10cm$ in diameter has a $2m$ length which is porous. In this porous section the velocity of exit is known to be constant $($Fig$.3\mathrm{.}13).$ If the velocities at inlet and outlet of the porous section are $2\mathrm{.}0\frac{m}{s}$ and $1\mathrm{.}2\frac{m}{s}$ respectively, estimate $($i$)$ the discharge emitted out through the walls of the porous pipe and $($ii$)$ the average velocity of this emitted discharge.

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