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

1. For a channel to be economic which of the following parameters should be minimum.

a) Wetted perimeter

b) Wetted area

c) Section factor

d) Hydraulic depth

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Explanation: If the wetted perimeter is minimum, amount of materials required for construction of the channel is less and hence the channel is more economical.

2. A rectangular channel section has depth y and width B, calculate the most economical area of the channel.

a) 2y^{2}

b) y^{2}

c) By

d) B^{2}

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3. The depth and widths of a rectangular channel section are y and B respectively, determine the economical perimeter of the section.

a) y

b) 2y

c) 3y

d) 4y

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4. Calculate the hydraulic radius for the most economical rectangular section having depth y and width B.

a) y/2

b) y

c) 2y

d) 3y

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5. Calculate the maximum discharge through a rectangular channel having depth 3m, bed slope of 1 in 1000.

a) 33.85m^{3}/s

b) 34.85m^{3}/s

c) 35.85m^{3}/s

d) 36.85m^{3}/s

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6. Calculate the maximum discharge through a rectangular channel having width of 5m, bed slope of 1 in 500 and manning’s co efficient is 0.020.

a) 33.43m^{3}⁄s

b) 32.43m^{3}⁄s

c) 31.43m^{3}⁄s

d) 30.43m^{3}⁄s

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7. The maximum discharge through a rectangular channel is 7.15m^{3}⁄s, determine the depth of the channel where S_{0} = 1/2000 and C=40.

a) 4m

b) 3m

c) 2m

d) 1m

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8. The base width of a most economical rectangular channel is 8m, calculate the hydraulic radius of the channel,

a) 5m

b) 4m

c) 3m

d) 2m

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Explanation: B = 2y; y = 4m

R = y/2 = 2m.

9. Calculate the section factor for the most economical rectangular section having depth of 4m.

a) 32

b) 64

c) 128

d) 256

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Explanation: Z = A√D = 2y

^{2}√y = 2y

^{5/2}

Z = 64.

10. The ratio between maximum discharge and top width of a rectangular channel is 91:50, calculate the depth of the channel if the bed slope is 1 in 3000 and C = 50.

a) 2m

b) 3m

c) 4m

d) 5m

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11. The ratio between normal discharge and maximum discharge through a rectangular channel is 32:6, calculate the depth of the channel if the width of the channel is 4m and bed slope, chezy’s constant remains same.

a) 1m

b) 2m

c) 3m

d) 4m

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12. The hydraulic radius of an economical rectangular section is 4m, calculate the discharge through the channel if the bed slope of the channel is 1 in 1000 and manning’s co efficient is 0.015.

a) 680m^{3}⁄s

b) 690m^{3}⁄s

c) 700m^{3}⁄s

d) 710 m^{3}⁄s

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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__.