$(2)$

A simple flow system to be used for steady$-$flow tests consists of a constant head tank connected to a length of $4-$mm$-$diameter tubing as shown in the figure below. The liquid has a viscosity of $0\mathrm{.}015\frac{(N)*(s)}{m^2},$ a density of $1200\frac{(kg)}{m^3},$ and discharges into the atmosphere with a mean velocity of $2\frac{(m)}{(s)}.($a$)$ Verify that the flow will be laminar. $($b$)$ The flow is fully developed in the last $3$ m of the tube. What is the pressure at the pressure gage? $($c$)$ What is the magnitude of the wall shearing stress, ${}_{rz},$ in the fully developed region?

the cinucal $$eynoias number for now in a pipe is $2100.$