$(3)$ Consider a $2$D steady incompresible frow of fluid through a rectangulan channel. The velocity components in the $x$&$y$ directions are given as $u=\frac{1}{4}{y}^2-2y^3$&$v=0\mathrm{.}5x$

& has a dynamic viscosity $(M)$ of $1$ poise. The dimensions of the channel are $L=2m$ in the $x-$direction & $H=1m$ in the $y-$direction. Calculate the shear stress at a point in the fluid.