$23$ Water flows through a Venturi section as shown. A mercury manometer is connected across two taps in the upstream pipe and the throat section. Given that the diameters of the pipe and throat are $4$ in$.$ and $2$ in$.,$ respectively, $h=0\mathrm{.}2m,{}_{Hg}=133,000\frac{N}{m^3}.$ Assume inviscid, incompressible, steady flow, and velocity distribution at every cross section is uniform. What is the velocity in the upstream pipe?