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GATE 2026 CE (CE1) – Question 40

Hydraulics · Channel hydraulics: specific energy, critical flow, uniform flow, hydraulic jump · 2 marks · Multiple choice

For a hydraulic jump formed in a rectangular horizontal channel, the sequent depth ratio is 2. The Froude number of supercritical stream is

  1. $\sqrt{3}$
  2. $\sqrt{5}$
  3. $\sqrt{6}$
  4. $\sqrt{8}$

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Correct answer: (A) $\sqrt{3}$

Explanation

The sequent depth ratio is $\frac{y_2}{y_1} = \frac{1}{2}\left(\sqrt{1 + 8F_1^2} - 1\right)$. Setting it to 2 gives $\sqrt{1 + 8F_1^2} = 5$, so $8F_1^2 = 24$ and $F_1 = \sqrt{3}$.