This set of Fluid Mechanics Questions and Answers for Campus interviews focuses on “Discharge over a Rectangular Notch, Triangular Notch, Trapezoidal Notch and Stepped Notch”.

1. Find the discharge of water flowing over a rectangular notch of 1.5 m length when the constant head over the notch is 275 mm. Take Cd = .60

a) 400 lit/s

b) 465 lit/s

c) 385 lit/s

d) 575 lit/s

View Answer

Explanation: Q = 2/3 * L * √2g * H

^{1.5}

= .67 * 1.5 * √19.62 * .275

^{1.5}

= .385 m

^{3}/min.

2. The head of water over a rectangular notch is 900 mm. The discharge is 300 litres/s. Find the length of the notch, when CD =.62

a) .192 m

b) .250 m

c) .205 m

d) .175 m

View Answer

Explanation: L = 1.5 * Q / (Cd * √2g * H

^{ 1.5})

= 1.5 * .3 / (.62 * √19.62 * .9

^{1.5})

= .192 m.

3. Find the discharge of water flowing over a rectangular notch of 1.3 m length when the constant head over the notch is 255 mm. Take Cd = .62

a) 400 lit/s

b) 465 lit/s

c) 385 lit/s

d) 575 lit/s

View Answer

Explanation: Q = 2/3 * L * √2g * H

^{1.5}

= .67 * 1.3 * √19.62 * .255

^{1.5}

= .385 m

^{3}/min.

4. The head of water over a rectangular notch is 700 mm. The discharge is 200 litres/s. Find the length of the notch, when CD =.63

a) .125 m

b) .265 m

c) .250 m

d) .200 m

View Answer

Explanation: L = 1.5 * Q / (Cd * √2g * H

^{1.5})

= 1.5 * .2 / (.62 * √19.62 * .7

^{1.5})

= .125 m.

5. Find the discharge over triangular notch of angle 50° when the head over the V notch

a) .93 m^{3}/min

b) 1.45 m^{3}/min

c) .88 m^{3}/min

d) .90 m^{3}/min

View Answer

Explanation: Q = 8/15 * √2g * H

^{1.5}* tan(x)

Here, x is the angle.

= 8/15 * √19.62 * .22

^{1.5}* tan(50)

= .93 m

^{3}/min.

6. The expression for discharge for a right angled notch is more complex than rectangular notch.

a) True

b) False

View Answer

Explanation : The expression for discharge for a right angled notch is easier than rectangular notch.

7. The results of which are more accurate; rectangular notch or triangular weir.

a) Rectangular notch

b) Triangular weir

c) Both are equally accurate

d) Rectangular weir

View Answer

Explanation : The results of triangular notch are more accurate for low discharge.

8. What is main reading required in calculation for rectangular notch or weir.

a) H

b) x, x is angle

c) L

d) None of the mentioned

View Answer

Explanation : H i.e height is main reading required in calculation for rectangular notch or weir.

9. We need to obligatorily have ventilation in triangular notch.

a) True

b) False

View Answer

Explanation : We need not obligatorily have ventilation in triangular notch.

10. Rectangular notch may or may not have ventilation.

a) True

b) False

View Answer

Explanation : Rectangular notch must have ventilation.

**Sanfoundry Global Education & Learning Series – Fluid Mechanics.**

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