Fluid Mechanics Questions and Answers – Gradually Varied Flow(GVF) – 1

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Gradually Varied Flow(GVF) – 1”.

1. Which of the following assumptions about a GVF is false?
a) Channel is prismatic
b) Pressure distribution is hydrostatic
c) Flow characteristics change with time
d) Roughness co efficient is constant
View Answer

Answer: c
Explanation: In a GVF, the flow is steady and hence the flow characteristics does not change with time.

2. Calculate the total discharge though a rectangular channel having depth 2m and width 4m if the value of C = 50 and if the slope of the energy line is 0.00004.
a) 1.53 m3/s
b) 2.53 m3/s
c) 3.53 m3/s
d) 4.53 m3/s
View Answer

Answer: b
Explanation:
Find total discharge though rectangular channel having depth 2m & width 4m

3. Calculate Sf for a triangular channel if the depth of the channel is 5m and the side slope is 1H:2V. Given: Q = 5.80 m3/s , C = 40.
a) 0.00010
b) 0.00011
c) 0.00012
d) 0.00013
View Answer

Answer: c
Explanation:
Find Sf for a triangular channel if depth of channel is 5m & the side slope is 1H:2V
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4. Calculate the discharge through a trapezoidal channel section if the depth of the channel is 3m and the base width is 3m. Given: C = 30, Sf = 0.0005, A = 12m2.
a) 6.10 m3/s
b) 7.10 m3/s
c) 8.10 m3/s
d) 9.10 m3/s
View Answer

Answer: d
Explanation:
Find discharge through trapezoidal channel section if depth is 3m & the base width is 3m

5. The discharge through a circular channel section having diameter 4m which is running half is 4.35 m3/s and the value of slope of energy line is Sf = 0.0003, calculate the value of C.
a) 50
b) 45
c) 40
d) 35
View Answer

Answer: c
Explanation:
The value of C is 40 if value of slope of energy line is Sf = 0.0003
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6. Determine the dynamic equation for the rate of change of depth having bed slope S0 and slope of total energy line Sf.
a) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-\frac{QT}{gA^2}}\)
b) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-\frac{Q^2T}{gA^2}}\)
c) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-\frac{Q^2T}{gA^3}}\)
d) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-\frac{Q^2T}{gA}}\)
View Answer

Answer: c
Explanation:
Find dynamic equation for rate of change of depth having bed slope S0

7. Determine the dynamic equation for the rate of change of depth having bed slope S0 and slope of total energy line Sf in terms of Froude’s number.
a) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-F_r^2}\)
b) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-F_r}\)
c) \(\frac{dy}{dx} = \frac{S_0-S_f}{1-\sqrt{F_r}}\)
d) \(\frac{dy}{dx} = \frac{S_0-S_f}{F_r^2}\)
View Answer

Answer: a
Explanation:
Dynamic equation for rate of change of depth & slope of total energy is dydx=S0−Sf1−F2
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8. Estimate the rate of change of specific energy having bed slope S0 and slope of total energy line Sf.
a) \(\frac{dE}{dx}\) = Sf – S0
b) \(\frac{dE}{dx}\) = Sf – \(\frac{S_0}{2}\)
c) \(\frac{dE}{dx}\) = S0 – Sf
d) \(\frac{dE}{dx} = \frac{S_f}{2}\) – S0
View Answer

Answer: c
Explanation:
Find rate of change of specific energy having bed slope S0 & slope of total energy line

9. Calculate the rate of change of specific energy if the bed slope is 1 in 1000 and Sf = 0.00007.
a) 6.3×10-3m
b) 7.3×10-3m
c) 8.3×10-3m
d) 9.3×10-3m
View Answer

Answer: d
Explanation:
Find the rate of change of specific energy if the bed slope is 1 in 1000 & Sf = 0.00007

10. Estimate the value of Sf if the value of bed slope is 1 in 800 and and dEdx = 10-3m.
a) 0.00015
b) 0.00025
c) 0.00035
d) 0.00045
View Answer

Answer: b
Explanation: dEdx = S0 – Sf; Sf = 0.00025.
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Sanfoundry Global Education & Learning Series – Fluid Mechanics.

To practice all areas of Fluid Mechanics, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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