Fluid Mechanics Multiple Choice Questions on “Manning’s Equation – 1”.
1. A rectangular channel is having depth 2m and width 3m, bed slope of 1 in 700. The value of manning’s roughness co efficient (n) is 0.06, estimate the discharge through the channel.
a) 2.42m3⁄s
b) 3.42m3⁄s
c) 4.42m3⁄s
d) 5.42m3⁄s
Answer: b
Clarification: 
2. Estimate the discharge through a triangular channel having depth 7m and side slope 1H:5V in which the bed slope is 1 in 1000. Manning’s co efficient = 0.03.
a) 8.07m3⁄s
b) 9.07m3⁄s
c) 10.07m3⁄s
d) 11.07m3⁄s
Answer: a
Clarification: 
3. The base width and the depth of a trapezoidal channel is 9m and 5m respectively. Calculate the discharge through a channel if the side slope of the channel is 1H:4V and the bed slope is 1 in 500. (n=0.04)
a) 109.73m3⁄s
b) 110.73m3⁄s
c) 111.73m3⁄s
d) 112.73m3⁄s
Answer: a
Clarification:
4. A circular channel section has diameter of 6m and it is running half. Calculate the discharge through the channel if the bed slope is 1 in 600 and manning’s co efficient is equal to 0.014.
a) 52m3⁄s
b) 53m3⁄s
c) 54m3⁄s
d) 55m3⁄s
Answer: c
Clarification:
5. The diameter of a circular channel section which is running full is 8m. Determine the discharge through the channel section if the bed slope is 1 in 600 and the value of the manning’s co efficient is 0.013.
a) 249.45m3⁄s
b) 250.45m3⁄s
c) 251.45m3⁄s
d) 252.45m3⁄s
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Answer: b
Clarification:
6. The area of a channel section is 8m2 and the wetted perimeter is 8m. Calculate the value of the bed slope of the channel if the discharge is 33.33m3⁄s and manning’s co efficient is 0.012.
a) 1 in 300
b) 1 in 400
c) 1 in 500
d) 1 in 600
Answer: b
Clarification:
7. The area of the triangular section is 66.67m2 and the wetted perimeter of the section is 24.03m. Calculate the value of the manning’s roughness co efficient if the bed slope of the channel section is 1 in 500 and the discharge through the channel is 117.61m3⁄s.
a) 0.03
b) 0.04
c) 0.05
d) 0.06
Answer: c
Clarification:
