At a point in a rectangular channel $15\mathrm{.}2$ m wide, $2\mathrm{.}1$ m deep, and $0\mathrm{.}00015$ bed slope, the discharge is $20\frac{m^3}{sec}$ and $n=0\mathrm{.}02($metric$).$ Show whether:

a$)$ the flow is uniform or non$-$uniform.

b$)$ the flow is super critical or sub critical.