Question

At a hydraulic jump, the flow depths are 0.4 m and 5 m at upstream and downstream, respectively. The channel is wide rectangular. The discharge per unit width is nearly

• A. $7.3m^2/s$
• B. $8.3m^2/s$
• C. $5.8m^2/s$
• D. $6.4m^2/s$

Answer 1

The correct option is A $7.3m^2/s$

$\begin{array}{cc}\frac{2q^2}{g}& =y_1{y}_2(y_1+y_2)\\ \frac{2q^2}{9.8}& =0.4\times 5(0.4+5)=2\times 5.4=10.8\\ q& =\sqrt{\frac{10.8\times 9.8}{2}}=7.3m^2/s\end{array}$