In a dynamic equation for GVF in a channel, the water surface slope relative to bottom, bed slope of channel and slope of total energy line are respectively 0.01, 0.025 and 0.020. The Froude number for this flow would be
- A0.707Correct
- B1.414
- C2.828
- D5.656
Solution
Concept
dy/dx = (S₀ − Sf)/(1 − Fr²)
Formula
dy/dx = (S₀ − Sf)/(1 − Fr²)
Step-by-step solution
1. dy/dx = 0.01, S₀ − Sf = 0.025 − 0.020 = 0.005. 2. 1 − Fr² = 0.005/0.01 = 0.5. 3. Fr² = 0.5, Fr = 0.707.
Explanation
Direct use of the dynamic equation.
Why the other options are wrong
The other values do not satisfy it.
Shortcut
1 − Fr² = (S₀ − Sf)/(dy/dx).
Correct answer: A) 0.707