Specific Energy Questions and Answers

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Specific Energy – 2”.

1. The dimensions of a rectangular channel are 3m in depth and 4m in width. Calculate the bed slope of the channel if the specific energy is 3.13m. [C=50]
a) 1 in 1000
b) 1 in 1100
c) 1 in 1200
d) 1 in 1300
View Answer

Answer: c
Explanation:

Find the bed slope of the channel if the specific energy is 3.13m

2. The depth of a trapezoidal channel section is 2m, base width of 3m and has a side slope of 1H:2V. Calculate n if the bed slope is 1 in 1000.
a) 0.012
b) 0.013
c) 0.014
d) 0.015
View Answer

Answer: b
Explanation:

Find n if the bed slope is 1 in 1000 if depth of a trapezoidal channel section is 2m

3. The specific energy of a channel section is 1.01m and the velocity of flow is 0.5m⁄s, calculate the depth of flow.
a) 0.8m
b) 1.0m
c) 1.2m
d) 1.4m
View Answer

Answer: b
Explanation:

The depth of flow is 1.0m if specific energy of a channel section is 1.01m

4. Calculate the velocity of flow through a channel having depth of 1.2m and specific energy equal to 1.24m.
a) 0.6 m/s
b) 0.7 m/s
c) 0.8m/s
d) 0.9m/s
View Answer

Answer: d
Explanation:

Find velocity of flow having depth of 1.2m & specific energy equal to 1.24m

5. What is the equation of the curve AB?

a) y + \(\frac{Q^2}{2gy}\)
b) y + \(\frac{Q}{2gy}\)
c) y + \(\frac{Q^2}{2gy^2}\)
d) y + \(\frac{Q}{2gy^2}\)
View Answer

Answer: d
Explanation: The curve AB (Specific Energy curve) is the combination of a parabola and a straight line, hence the valid equation is
y + \(\frac{Q}{2gy^2}\)

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6. What are y1 and y2 in the adjoining graph?

a) Conjugate depths
b) Alternate depths
c) Equal depths
d) Sequent depths
View Answer

Answer: b
Explanation: For a particular specific energy above the minimum specific energy there are two depths called as alternate depths.

7. The specific energy of a rectangular channel having dimensions 2m×3m is 3.095m. Calculate the friction factor.
a) 0.01
b) 0.02
c) 0.03
d) 0.04
View Answer

Answer: c
Explanation:

Friction factor is 0.03 if specific energy of rectangular having dimensions is 3.095m

8. Calculate the average shear stress for a rectangular channel having depth 0.5m, width 0.8m if the specific energy is 0.56m.
a) 2.32 N/m²
b) 3.32 N/m²
c) 4.32 N/m²
d) 5.32 N/m²
View Answer

Answer: c
Explanation:

Find the average shear stress for a rectangular channel having depth 0.5m, width 0.8m

9. Calculate the specific energy for the most economical rectangular channel having depth 2m and width 4m if the bed slope of the channel is 1 in 1200. C = 35.
a) 2.05m
b) 3.05m
c) 4.05m
d) 5.05m
View Answer

Answer: a
Explanation:

Find the specific energy for rectangular channel having depth 2m & width 4m

10. Estimate the specific energy for the most economical trapezoidal channel section having depth of 5m, side slope of 1H:4V and bed slope of 1 in 1200.
a) 1.14m
b) 2.14m
c) 3.14m
d) 4.14m
View Answer

Answer: b
Explanation: