A thin plate moves between two parallel horizontal stationary flat plates at a constant velocity of $5$ m$/$s$.$ The two stationary flat plates are $4$ mm apart, and the medium between them is filled with oil whose viscosity is $0\mathrm{.}9$ Pa$-$s$.$ The part of the plate immersed in oil at any given time is $2-$m long, and $0\mathrm{.}5$ m wide. If the thin plate is placed equidistant from both plates above and below it$,$ calculate the drag force required to maintain its motion.$(50$ points$)$