PROBLEM $3\mathrm{.}14$:

Width of AB gate is $2m.$ There is a hinge at A$.$ According to this, calculate the force with its direction to be applied to $B,$ for the following conditions:

a$)$ There is water at both sides. $({}_{\text{w}\text{a}\text{t}\text{e}\text{r}}=9\mathrm{.}81k\frac{N}{m^3})$

b$)$ There is oil at both sides. $({}_{\text{o}\text{i}\text{l}}=7\mathrm{.}85k\frac{N}{m^3})$