Economic Circular Section Questions and Answers

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Most Economic Circular Section – 2”.

1. Estimate the hydraulic depth for a most economical circular channel section in case of maximum velocity.
a) 0.2D
b) 0.3D
c) 0.4D
d) 0.5D
View Answer

Answer: b
Explanation:

Hydraulic depth for economical circular channel section in maximum velocity is 0.3D

2. What is the value of θ in a most economical circular section in case of maximum discharge?
a) 150°
b) 152°
c) 154°
d) 156°
View Answer

Answer: c
Explanation: The equation in case for maximum discharge is,
4Ɵ – 6θ cos⁡ 2θ + sin ⁡2θ = 0 where θ = 154°.

3. Calculate the depth in a most economical circular section in case of maximum discharge.
a) 0.65D
b) 0.75D
c) 0.85D
d) 0.95D
Answer: d
View Answer

Answer: d
Explanation:

The depth in a most economical circular section in case of maximum discharge is 0.95D

4. Calculate the hydraulic radius of a circular channel in case of maximum discharge if the radius of the channel is 4m.
a) 1.7m
b) 2.0m
c) 2.3m
d) 2.6m
View Answer

Answer: c
Explanation:

Hydraulic radius of circular of maximum discharge if radius of channel is 4m is 2.3m

5. Calculate the wetted area of a circular channel section in case of maximum velocity.
a) 5.47m²
b) 6.47m²
c) 7.47m²
d) 8.47m²
View Answer

Answer: a
Explanation:

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6. Calculate the wetted perimeter of the most economical circular section having radius 3m in case of maximum discharge.
a) 15.12m
b) 16.12m
c) 17.12m
d) 18.12m
View Answer

Answer: b
Explanation: P = 2Rθ = 2(3)(2.6864) = 16.12m.

7. What is the value of wetted perimeter of a circular section having radius 6m in case of maximum velocity?
a) 12.47m
b) 13.47m
c) 14.47m
d) 15.47m
View Answer

Answer: b
Explanation: P = 2Rθ = 2(6)(2.2460) = 13.47m.

8. Estimate the value of wetted area of a circular section in case of maximum discharge if the radius of the channel is 7m.
a) 134m²
b) 144m²
c) 154m²
d) 164m²
View Answer

Answer: a
Explanation:

9. Calculate the hydraulic radius in case of maximum velocity if the radius of the section is 8m.
a) 7.87m
b) 6.87m
c) 5.87m
d) 4.87m
View Answer

Answer: d
Explanation:

10. Calculate the discharge through a most economical circular section in case of maximum velocity if the radius of the channel is 0.5m, bed slope of 1 in 500 and the value of n = 0.016.
a) 0.43 m³/s
b) 0.53 m³/s
c) 0.63 m³/s
d) 0.73 m³/s
View Answer

Answer: a
Explanation: