A $4m7m$ rectangular gate is located on the sloping side of a water reservoir such that the $4-m$

side of the gate is parallel to the water surface. The side of the reservoir $($and the gate$)$ slopes at an

angle of $50$ to the horizontal, and the top of the gate is $3\mathrm{.}5m$ vertically below the water surface.

Estimate the resultant hydrostatic force on the gate and the effective location of this resultant force,

as measured vertically downward from the water surface. For water, $=9\mathrm{.}79k\frac{N}{m^3}$; For a

rectangle, $I=\frac{b{d}^3}{12},$ where $b$ is the side parallel to the water surface.

A$.$ Draw a diagram to illustrate the forces and position of gate in the water storage reservoir.

$[4$ marks$]$