GATE 2018 CE (CE1) – Question 33
A 10 m wide rectangular channel carries 20 m³/s at critical depth. With g = 9.81 m/s², specific energy, to two decimals, is ______ m.
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Correct answer: 1.10 to 1.20
Explanation
Unit discharge is $q=20/10=2$ m²/s. Critical depth is $y_c=(q^2/g)^{1/3}=(4/9.81)^{1/3}=0.74153$ m. Critical specific energy is $3y_c/2=1.1123$ m, or 1.11 m.