Hydraulic and Fluid Mechanics

71. A weir is said to be broad crested weir, if the width of the crest of the weir is

  1. Equal to
  2. Less than
  3. More than
  4. None of these

Correct answer: (C)
More than

72. A weir is said to be narrow-crested weir, if the width of the crest of the weir is

  1. half the height of water above the weir crest.
  2. Equal to
  3. More than
  4. None of these

Correct answer: (B)
Equal to

73. A weir, generally, used as a spillway of a dam is

  1. Narrow crested weir
  2. Broad crested weir
  3. Ogee weir
  4. Submerged weir

Correct answer: (C)
Ogee weir

74. According to Bazin's formula, the discharge over a rectangular weir is mL2g x H3/2where m is equal to

  1. 0.405 + (0.003/H)
  2. 0.003 + (0.405/H)
  3. 0.405 + (H/0.003)
  4. 0.003 + (H/0.405)

Correct answer: (A)
0.405 + (0.003/H)

75. According to Bernoulli's equation

  1. Z + p/w + v2/2g = constant
  2. Z + p/w - v2/2g = constant
  3. Z - p/w + v2/2g = constant
  4. Z - p/w - v2/2g = constant

Correct answer: (A)
Z + p/w + v2/2g = constant

76. According to Bernoulli's equation for steady ideal fluid flow

  1. Principle of conservation of mass holds
  2. Velocity and pressure are inversely proportional
  3. Total energy is constant throughout
  4. The energy is constant along a streamline but may vary across streamlines

Correct answer: (D)
The energy is constant along a streamline but may vary across streamlines

77. According to Chezy's formula, the discharge through an open channel is (where A = Area of flow, C = Chezy's constant, m = Hydraulic mean depth, and i = Uniform slope in bed)

  1. A × √(m × i)
  2. C × √(m × i)
  3. AC × √(m × i)
  4. mi × √(A × C)

Correct answer: (C)
AC × √(m × i)

78. According to Darcy's formula, the loss of head due to friction in the pipe is (where f = Darcy's coefficient, l = Length of pipe, v = Velocity of liquid in pipe, and d = Diameter of pipe)

  1. flv2/2gd
  2. flv2/gd
  3. 3flv2/2gd
  4. 4flv2/2gd

Correct answer: (D)
4flv2/2gd

79. According to equation of continuity,

  1. w1a1 = w2a2
  2. w1v1 = w2v2
  3. a1v1 = a2v2
  4. a1/v1 = a2/v2

Correct answer: (C)
a1v1 = a2v2

80. According to Francis formula, the discharge over a rectangular weir is (where n = Number of end contractions)

  1. (2/3) × Cd (L - nH) × √(2gh)
  2. (2/3) × Cd (L - 0.nH) × √(2g)xH3/2
  3. (2/3) × Cd (L - nH) × √(2g) xH2
  4. (2/3) × Cd (L - nH) × √(2g) xH5/2

Correct answer: (B)
(2/3) × Cd (L - 0.nH) × √(2g)xH3/2

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