$4\mathrm{.}6\mathrm{.}28$ Water $($assumed inviscid and incompressible$)$ flows steadily

with a speed of $3\frac{m}{s}$ from the large tank shown in Fig. P$4\mathrm{.}6\mathrm{.}28.$

Determine the depth, $H,$ of the layer of light liquid $($specific weight $=$

$7854\frac{N}{m^3})$ that covers the water in the tank.