A long solid cylinder of radius $0\mathrm{.}8$ m hinged at point A is used as an automatic gate, as

shown in Figure Q$4.$ When the water level reaches $5$ m $,$ the gate opens by tuming

about the hinge at point $A.$ Determine:

$($a$)$ the hydrostatic force acting on the cylinder and its line of action when the gate

opens and

$($Answer: $F_W=36\mathrm{.}1kN,F_R=52\mathrm{.}3kN,=46\mathrm{.}4)$

$($b$)$ the weight of the cylinder per m length of the cylinder.

Answar: $($:$W_{\text{@}}=37\mathrm{.}9kN$