$3(20$ points$)$ A channel of rectangular section, $4ft$ wide, discharging water at

a rate of $48f\frac{t^3}{s}$ with an average velocity of $4\mathrm{.}0f\frac{t}{s}.$

a$)$ What is the specific energy of the flow in the channel?

b$)$ What is the depth of flow when the specific energy is minimum?

c$)$ What is the velocity of flow when the specific energy is minimum?

d$)$ What is the minimum specific energy of the flow?

e$)$ What is the type of flow $($subcritical$,$ critical, or super critical$)?$