A metal container $2$ m high, with an inside cross$-$sectional area of $1m^2$ weighs $5$ N when empty. The container is placed on a scale and water flows in through an opening in the top and out through the two equal$-$area openings in the sides, as shown in the diagram. Under steady flow conditions, the height of the water in the tank is $h=1\mathrm{.}9m.$ Take $A_1=0\mathrm{.}1m^2,V=-10j\frac{m}{s}$ and $A_2=A_3=0\mathrm{.}1m^2.$ Find $R_v$