A $21\mathrm{.}8m$ rectangular gate is holding water with $12\mathrm{.}1$ m depth in a reservoir as shown in the figure below.

a$)$ Calculate the force $P$ that we must apply at the bottom of the gate in order to keep the gate closed.

b$)$ Could you conceptualize a different design $($location$)$ for the hinge of the gate in order for the required force $P$ to be minimal?