Question $11.$ A rectangular channel $3m$ wide and $1\mathrm{.}25m$

deep is flowing at steady state. The channel momentum

is $4\mathrm{.}5m3.$ The discharge of the channel is most nearly

$($A$)5\mathrm{.}3m\frac{3}{s}$

$($B$)5\mathrm{.}5m\frac{3}{s}$

$($C$)6\mathrm{.}6m\frac{3}{s}$

$($D$)8\mathrm{.}9m\frac{3}{s}$