Current Attempt in Progress

$($Force on plane surface$)$ The rectangular gate $CD$ of the figure below is $1\mathrm{.}9m$ wide and $2\mathrm{.}0m$ long. Assuming the material of the gate to be homogeneous and neglecting friction at the hinge $C,$ determine the weight of the gate necessary to keep it shut until the water level rises to $2\mathrm{.}0m$ above the hinge.

$W=,kN$