Question

A trapezoidal channel with bottom width of 3 m and side slope of 1V: 1.5 H carries a discharge of 8.0 $m^3/sec$ with the flow depth of 1.5 m. The Froude Number of the flow is

• A. 0.066
• B. 0.132
• C. 0.528
• D. 0.316

Answer 1

The correct option is D 0.316


$Q=8m^3/s$

$A=\frac{1}{2}(3+7.5)\times 1.5=7.875m^2$

$V=\frac{Q}{A}=\frac{8}{7.875}=1.015m/s$

$Now\frac{1}{1.5}=\frac{1.5}{X}$

$orx=2.25$

$T=3+2\times 2.25=7.5m$

$D=\frac{A}{T}=\frac{7.875}{7.5}=1.05$

$F=\frac{V}{\sqrt{gD}}=\frac{1.05}{\sqrt{9.81\times 1.05}}=0.316$