Question

Water flows at a depth of 0.1 m with a velocity of 6 m/s in a rectangular channel. The alternate depth is

• A. 0.86 m
• B. 0.81 m
• C. 1.93 m
• D. 0.40 m

Answer 1

The correct option is C 1.93 m

It should be 'conjugate depth' or 'sequent depth' in place of 'alternate depth'. If we are asked to calculate alternate depth.

$E_1=E_2$
$0.1+\frac{6^2}{2\times 9.81}=y_2+\frac{V_2^2}{2g}$

$=Y_2+\frac{Q^2}{2g{y}_2^2.B^2}$

$=Y_2+\frac{q^2}{2g{y}_2^2}$

$=Y_2+\frac{(6\times 0.1{)}^2}{2g{y}_2^2}$

On solving by trial and error we get
$Y_2=1.93m$