Fluid Mechanics

131.Check valves are used

  1. At high pressure
  2. In bends
  3. For controlling water flow
  4. For unidirectional flow
Correct answer: (D)
For unidirectional flow

132.Choking in case of pipe flow means that a

  1. Specified mass flow rate cannot be achieved
  2. Valve is closed in the line
  3. Restriction in flow cross-section area occurs
  4. None of these
Correct answer: (A)
Specified mass flow rate cannot be achieved

133.Choose the correct set of dimensions of viscosity that are equivalent (where, F, M, L, T are dimensions for force, mass, length and time respectively).

  1. FL-2T, ML-1T-1
  2. FLT, ML-1T-1
  3. ML-1T-3, F-1L2T
  4. F-1L2T-1, MLT-3
Correct answer: (A)

FL-2T, ML-1T-1

134.Choose the set of pressure intensities that are equivalent.

  1. 4.33 psi, 10 ft. of water, 8.83 inches of Hg
  2. 4.33 psi, 10 ft. of water, 20.7 inches of Hg
  3. 10 psi, 19.7 ft. of water, 23.3 inches of Hg
  4. 10 psi, 19.7 ft. of water, 5.3 inches of Hg
Correct answer: (A)
4.33 psi, 10 ft. of water, 8.83 inches of Hg

135.Cocks are used to control

  1. Water
  2. Any liquid
  3. Solids
  4. None of these
Correct answer: (B)
Any liquid

136.Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about

  1. 0.42
  2. 0.62
  3. 0.82
  4. 0.98
Correct answer: (B)
0.62

137.Co-efficient of velocity is _________ the coefficient of discharge.

  1. Less than
  2. More than
  3. Equal to
  4. Not related to
Correct answer: (B)
More than

138.Colebrook equation for friction factor in turbulent flow is given by, f-0.5 = -4 loge [(ε/D) + (1.26/NRe √F). It reduces to Nikuradse equation for a value of (ϵ/D) equal to

  1. 0
  2. 1
  3. ∞
  4. 0.5
Correct answer: (B)
1

139.Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the _________ decreases.

  1. NPSH required
  2. BHP required by the pump
  3. Head of the liquid pumped
  4. All (A), (B) and (C)
Correct answer: (D)
All (A), (B) and (C)

140.Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement.

  1. ƒ1 = ƒ2
  2. ƒ1 < ƒ2
  3. ƒ1 > ƒ2
  4. Data not sufficient to relate ƒ1 & ƒ2
Correct answer: (C)
ƒ1 > ƒ2
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