A vertical rectangular gate, $1m$ wide and $2m$ high, weighs $800N.$ It is on the face of the dam with the upper edge $4m$ below the water surface.

What is the total force, in $kN,$ of water on the gate?

A$.68\mathrm{.}67$

C$.88\mathrm{.}29$

B$.78,48$

D$.98\mathrm{.}10$

If the gate is hinged at the top, how much horizontal force, in $kN,$ applied at the bottom is needed to open it$?$

A$.52\mathrm{.}48$

c$.60\mathrm{.}82$

B$.56\mathrm{.}90$

D$.65\mathrm{.}24$

If the gate is opened by sliding up the guides, how much vertical force, in $kN,$ is needed to open it assuming a friction coefficient of $0\mathrm{.}4$ between the gate and the guides?

A$.28\mathrm{.}27$

c$.36\mathrm{.}12$