Interview Questions on Fluid Mechanics

1.Laminar flow of a Newtonian fluid ceases to exist, when the Reynolds number exceeds
  1. 4000
  2. 2100
  3. 1500
  4. 3000

Answer:B

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2. Which one is in a state of failure?
  1. Solid
  2. Liquid
  3. Gas
  4. Fluid
Gas

Answer:D

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3. In which device the momentum generated by one fluid is used for moving another fluid
  1. jet pump
  2. Blower
  3. acid egg
  4. none of these

Answer:A

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4. Which element would regain its original shape if a small shear force is applied on it and then removed
  1. Solid
  2. Liquid
  3. Fluid
  4. Gaseous

Answer:A

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5. The normal stress is the same in all directions at a point in a fluid, when the fluid is
  1. non-viscous.
  2. incompressible.
  3. both (a) and (b).
  4. not having any relative motion with respect to the other fluid layer

Answer:D

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6. N. second/m2 is
  1. the S.I. unit of dynamic viscosity.
  2. the S.I. unit of kinematic viscosity.
  3. equivalent to one poise.
  4. equivalent to one stoke.

Answer:A

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7. If a person studies about a fluid which is at rest, what will you call his domain of study?
  1. Fluid Mechanics
  2. Fluid Statics
  3. Fluid Kinematics
  4. Fluid Dynamics

Answer:B

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8. The terminal velocity of a particle moving through a fluid varies as dpn. What is the value of n' for Newton's law regime ?
  1. 0.5
  2. 1
  3. 1.5
  4. 3

Answer:A

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9. Dimension of absolute viscosity is
  1. ML-1T-1
  2. MLT-1
  3. ML-1T
  4. MLT

Answer:A

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10. Which one of the following is the dimension of mass density?
  1. [M1 L-3 T 0].
  2. [M1 L3 T0].
  3. [M0 L-3 T0].
  4. [M0 L3 T0].

Answer:A

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11. Due to which property the mercury does not wet the glass
  1. surface tension
  2. Viscosity
  3. Cohesion
  4. Adhesion

Answer:A

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12. Head developed by a centrifugal pump depends on its
  1. Speed
  2. impeller diameter
  3. both (a) and (b)
  4. neither (a) nor (b)

Answer:C

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13. The head loss in turbulent flow in a pipe varies
  1. as velocity
  2. as (velocity)2
  3. inversely as the square of diameter
  4. inversely as the velocity

Answer:B

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14.Most commonly used joint in the underground pipe lines is the
  1. sleevejoint
  2. coupling
  3. flange
  4. expansion joint

Answer:A

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15.Schedule number of a pipe, which is a measure of its wall thickness, is given by
  1. 1000 P'/S
  2. 100 P'/S
  3. 1000 S/P'
  4. 10000 P'/S

Answer:A

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16. The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the
  1. discharge.
  2. suction
  3. suction less the vapour pressure of the liquid at suction temperature.
  4. None of the above

Answer:C

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17. With increasing flow rate, the hydraulic efficiency of a centrifugal pump
  1. monotonically decreases.
  2. decreases and then increases.
  3. remains constant.
  4. increases and then decreases.

Answer:A

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18.During a weak jump, the value of Froude lies in between________
  1. 1 to 2.5
  2. 2.5 to 3.5
  3. Less than 1
  4. Zero

Answer:A

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19.The velocity profile for turbulent flow through a closed conduit is
  1. Logarithmic
  2. Parabolic
  3. Hyperbolic
  4. Linear

Answer:A

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20. In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. What property will be same for both if 2 pipes of same hydraulic roughness are compared
  1. relative roughness
  2. absolute roughness.
  3. friction co-efficient for flows at equal Reynold number.
  4. all (a), (b) & (c).

Answer:C

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21. In which type of matter, one won’t find a free surface?
  1. Solid
  2. Liquid
  3. Gas
  4. Fluid

Answer:C

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22. Molten soap mass is transported by a __________ pump.
  1. Diaphragm
  2. reciprocating
  3. Gear
  4. Centrifugal

Answer:D

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23. Which of the following denotes the effect of compressibility in fluid flow ?
  1. Weber number
  2. Mach number
  3. Euler number
  4. Reynolds number

Answer:B

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24. The specific volume of a liquid is the reciprocal of
  1. weight density
  2. mass density
  3. specific weight
  4. specific volume

Answer:B

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25. Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe.
  1. smaller than
  2. larger than
  3. same as
  4. Twice

Answer:A

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26. The terminal velocity of a small sphere settling in a viscous fluid varies as the
  1. first power of its dimeter.
  2. inverse of the fluid viscosity.
  3. inverse square of the diameter.
  4. None of the above

Answer:B

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27. If the discharge of a centrifugal pump is throttled, then its suction lift
  1. Increases
  2. Decreases
  3. remains unchanged
  4. data insufficient to predict

Answer:A

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28. Foot valves provided in pumps are __________ valves.
  1. Relief
  2. three/four way
  3. pressure reducing
  4. directional control

Answer:D

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29. At high Reynolds number
  1. inertial forces control and viscous forces are unimportant.
  2. viscous forces predominate.
  3. inertial forces are unimportant and viscous forces control.
  4. none of these.

Answer:A

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30. Power loss in an orificemeter is __________ that in a venturimeter.
  1. less than
  2. same as
  3. more than
  4. data insufficient, cannot be predicted

Answer:C

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31. What is the normal range of exit cone angle of a venturimeter ?
  1. 2 to 5
  2. 7 to 15
  3. 15 to 25
  4. >25

Answer:A

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32. A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke's law. What will be the settling velocity of a particle B having diameter of 20 microns in the same oil
  1. same as that of A.
  2. one fourth as that of A.
  3. twice as that of A.
  4. four times as that of A.

Answer:B

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33. The pitot static tube does not measure the __________ pressure.
  1. Static
  2. Total
  3. difference in static & dynamic
  4. all (a), (b) and (c)

Answer:D

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34. In fluid flow, cavitation is caused, if the
  1. fluid velocity decreases to zero.
  2. total energy decreases.
  3. both (a) and (b).
  4. flow pressure approaches its vapour pressure at the prevailing temperature.

Answer:D

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35. The ratio of the depth of flow to the hydraulic radius for the most economical trapezoidal section, in open channel flow is
  1. 0.5
  2. 1
  3. 1.5
  4. 2

Answer:D

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36. The drag co-efficient for a bacterium moving in water at 1 mm/s, will be of the following order of magnitude (assume size of the bacterium to be 1 micron and kinematic viscosity of water to be 10-6m2/s).
  1. 24000
  2. 24
  3. 0.24
  4. 0.44

Answer:D

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37. For Laminar flow through a packed bed, the pressure drop is proportional to (Vs is the superficial liquid velocity and Dp is the particle diameter)
  1. Vs/Dp2
  2. Vs2/Dp2
  3. Vs2/Dp3
  4. Vs/Dp3

Answer:A

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38. The maximum delivery pressure of compressors can be upto __________ atmospheres.
  1. 10
  2. 100
  3. 250
  4. 1000

Answer:D

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39. Dimension of surface tension is(where, F = force, L = length)
  1. FL-1
  2. F-1 . L
  3. F.L-2
  4. F-2 . L

Answer:A

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40. Which of the following is not a dimension-less parameter ?
  1. Euler number
  2. Specific gravity
  3. Fanning friction factor
  4. None of these

Answer:D

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41. Co-efficient of velocity is __________ the coefficient of discharge.
  1. less than
  2. more than
  3. equal to
  4. not related to

Answer:B

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42. All pipes of a particular nominal size have the same
  1. inside diameter
  2. outside diameter
  3. Thickness
  4. none of these

Answer:B

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43. For the transfer of solution of thick slurry, the pump used is a __________ pump.
  1. Reciprocating
  2. Gear
  3. Diaphragm
  4. Centrifugal

Answer:C

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44. Which one of the following is the dimension of specific gravity of a liquid?
  1. [M1 L-3 T0].
  2. [M1 L0 T0].
  3. [M0 L-3 T0].
  4. [M0 L0 T0].

Answer:D

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45. Which of the following is not concerned with the fluid-particle interaction ?
  1. Drag co-efficient
  2. Froude number
  3. Galileo number
  4. Weber number

Answer:D

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46. Pick out the wrong statement.
  1. Momentum transfer in laminar flow results from velocity gradient.
  2. A fluid in equilibrium is not free from shear stress.
  3. The viscosity of a non-Newtonion fluid is a function of temperature only.
  4. both (b) and (c)

Answer:D

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47. Pressure drag does not depend upon the
  1. roughness of surface of the body.
  2. pressure of main flow only.
  3. length of the body in flow direction.
  4. all (a), (b) and (c)

Answer:D

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48. Which one of the following is the dimension of specific weight of a liquid?
  1. [ML-3 T -2].
  2. ML3 T-2].
  3. [ML-2 T-2].
  4. [ML2 T-2].

Answer:C

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49. __________ pumps are axial flow pumps.
  1. Turbine
  2. Propeller
  3. Diffuser
  4. none of these

Answer:B

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50. During settling of a particle in a fluid for what range of particle size (in microns) would the Brownian movement be prominent
  1. 2 to 3
  2. 0.01 to 0.10
  3. 200 to 300
  4. 100 to 1000

Answer:A

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51. For a particle settling in water at its terminal settling velocity, which of the following is true ?
  1. Buoyancy = weight + drag
  2. Weight = buoyancy + drag
  3. Drag = buoyancy + weight
  4. Drag = weight

Answer:B

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52. A Bingham fluid of viscosity μ = 10 Pa.s and yield stress, τ0 = 10 KPa, is shared between flat parallel plates separated by a distance of 10-3 m. If the top most plate moves at 1 m/s then the shear stress on the plate would be
  1. 10 KPa
  2. 20 KPa
  3. 30 KPa
  4. 40 KPa

Answer:B

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53. Pick out the correct statement.
  1. The forced vortex happens when the fluid rotates as a solid about an axis.
  2. Newton's law of viscosity is not applicable on laminar flow.
  3. A free vortex occurs, when fluidrotates as a solid.
  4. None of the above

Answer:A

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54. Shear stress in a fluid flowing in a round pipe
  1. varies parabolically across the cross-section.
  2. remains constant over the cross-section.
  3. is zero at the centre and varies linearly with the radius.
  4. None of the above

Answer:C

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55. Which material is used for making resistance wire used in a hot wire anemometer
  1. Copper
  2. Tungsten
  3. Chromium
  4. Aluminium

Answer:B

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56. Two dimensional stream function
  1. relates velocity and pressure
  2. is constant along a stream line.
  3. is constant along an equipotential surface.
  4. none of these.

Answer:B

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57. What causes cavitation in centrifugal pump ?
  1. High suction pressure
  2. Low barometric pressure
  3. Low suction pressure
  4. High suction velocity

Answer:C

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58. Draining of shallow pits or sump is done by a sump pump, which is a __________ pump.
  1. single stage vertical
  2. Centrifugal
  3. Plunger
  4. Diffuser

Answer:A

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59. A hydraulic ram acts as a/an __________ pump.
  1. centrifugal
  2. reciprocating
  3. impulse
  4. parallel cylinder

Answer:C

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60. What is the ratio of avg. fluid velocity to max velocity in a laminar flow of a Newtonion fluid
  1. 0.5
  2. 1
  3. 2
  4. 0.66

Answer:A

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61. 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

Answer:A

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62. The discharge through a venturimeter depends upon
  1. pressure drop only.
  2. its orientation.
  3. co-efficient of contraction only.
  4. none of these.

Answer:A

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63. The line of action of the buoyant force passes through the centre of gravity of the
  1. submerged body.
  2. displaced volume of the fluid.
  3. volume of fluid vertically above the body.
  4. horizontal projection of the body

Answer:B

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64. The friction factor for turbulent flow in a hydraulically smooth pipe
  1. depends only on Reynolds number.
  2. does not depend on Reynolds number.
  3. depends on the roughness.
  4. none of these.

Answer:A

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65. The pressure at a point in a fluid is not the same in all directions, when the fluid is viscous and
  1. moving
  2. static
  3. cold
  4. hot

Answer:A

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66. Which among the following is formula for force when it acts along the direction of flow?
  1. pav 2 Sin2θ
  2. pav Sin2θ
  3. pa Sin2θ
  4. maE Sin2θ

Answer:A

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67. What causes convective acceleration in fluid flow ?
  1. Steep slope in flow
  2. Unsteady nature of flow
  3. Non-uniformity of flow
  4. Turbulence in flow

Answer:C

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68. The Stoke's stream function applies to the
  1. irrotational flow only.
  2. ideal/non-viscous fluids only.
  3. cases of axial symmetry.
  4. none of these.

Answer:C

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69. Slugging in a fluidised bed can be avoided by using
  1. tall narrow vessel.
  2. deep bed of solids.
  3. appropriate particle size and shallow beds of solid
  4. very large particles.

Answer:C

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70. The ratio of width to depth for the most economical rectangular section in open channel flow is
  1. 0.5
  2. 1
  3. 1.5
  4. 2

Answer:D

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71. The simple pitot tube measures the __________ pressure.
  1. static
  2. dynamic
  3. total
  4. none of these

Answer:C

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72. The mass of water per sec striking the plate is_________
  1. pav2
  2. pav
  3. pa
  4. maE

Answer:B

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73. Capacity of a hydraulic accumulator is defined in terms of maximum
  1. amount of energy stored.
  2. flow rate through accumulator.
  3. rate of falling of ram.
  4. volume available in the cylinder.

Answer:A

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74. With diminishing cross-sectional area in case of subsonic flow in a converging nozzle, the
  1. velocity increases
  2. pressure decreases
  3. both (a) & (b)
  4. neither (a) nor (b)

Answer:C

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75. If “Re” denotes Reynolds number then the boundary layer separation would be characterised by which condition
  1. Re << 1, accelerating flow
  2. Re >> 1, accelerating flow
  3. Re << 1, decelerating flow
  4. Re >>1, decelerating flow

Answer:D

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76. Manometers measure the __________ pressure.
  1. vacuum as well as the atmospheric
  2. difference in
  3. absolute
  4. gage

Answer:B

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77. Which of the following fluid forces are not considered in the Navier-Stoke's equation?
  1. Gravity forces
  2. Viscous forces
  3. Pressure forces
  4. Turbulent forces

Answer:D

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78. Which of the following may be termed as a variable orifice flowmeter ?
  1. Rotameter
  2. Pitot tube
  3. V-notch
  4. All (a), (b) and (c)

Answer:A

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79. If the fluid has specific weight of 10N/m3 for a volume of 100dm3 on a planet which is having acceleration due to gravity, g=20m/s2 then what will be its specific weight on a planet having a value of g= 4m/s2
  1. 5 N/m3
  2. 50 N/m3
  3. 2 N/m3
  4. 10 N/m3

Answer:C

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80. In turbulent flow, a rough pipe has the same friction factor as a smooth pipe
  1. in the zone of complete turbulence.
  2. when the roughness projections are much smaller than the thickness of the laminar film.
  3. everywhere in the transition zone.
  4. when the friction factor is independent of the Reynold's number.

Answer:B

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81. Air vessel provided in a reciprocating pump
  1. smoothens the flow by avoiding pulsations.
  2. increases the volumetric efficiency of the pump.
  3. saves the pump from the danger of cavitation.
  4. none of these.

Answer:D

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82. Bernoulli's equation is dependent on the
  1. first law of thermodynamics.
  2. third law of thermodynamics.
  3. law of conservation of momentum.
  4. none of these.

Answer:D

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83.The capacity of an accumulator is the maximum
  1. energy which it can store.
  2. discharge which it can deliver.
  3. liquid which it can store.
  4. none of these.

Answer:A

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84. With increase in the temperature, viscosity of a liquid
  1. increases
  2. decreases
  3. remains constant
  4. may increase or decrease; depends on the liquid

Answer:B

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85. Vena-contracta pressure tapping is at a distance __________ from the position of an orificemeter fitted in a pipe of internal diameter 'd'
  1. D
  2. 0.5 d
  3. 2d
  4. 4d

Answer:B

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86. The value of the surface tension of an ideal fluid is
  1. zero
  2. unity
  3. infinity
  4. more than that of a real fluid

Answer:A

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87. The pump impeller and the turbine runner in a hydraulic torque converter
  1. have the same diameter.
  2. have different diameters.
  3. are directly coupled.
  4. none of these.

Answer:B

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88. If two fluids 1 and 2 have mass densities of p1 and p2 and specific volumes v1 and v2 then
  1. v1 > v2
  2. v1 < v2
  3. v1 = v2
  4. Cannot be determined due to insufficient information.

Answer:B

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89. Reciprocating pumps compared to centrifugal pumps
  1. deliver liquid at uniform pressure.
  2. can handle slurries more efficiently.
  3. are not subject to air binding.
  4. can be operated with delivery valve closed.

Answer:C

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90. The fluid property which matters for fall-ing rain drops to acquire spherical shape is its
  1. pressure
  2. height of descend
  3. viscosity
  4. surface tension

Answer:D

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91. We cannot use a pitot tube to measure
  1. static pressure.
  2. dynamic pressure.
  3. velocity at the stagnation point.
  4. all (a), (b) and (c).

Answer:D

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92. Boundary layer separation occurs when the
  1. pressure reaches a minimum.
  2. cross-section of the channel is reduced.
  3. valve is closed in a pipeline.
  4. velocity of sound is reached.

Answer:B

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93. The head loss in turbulent flow in a pipe varies
  1. directly as the velocity.
  2. inversely as the square of the velocity.
  3. approximately as the square of the velocity.
  4. inversely as the square of the diameter.

Answer:C

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94. The actual velocity at the vena con-tracta during flow thru an orifice from a reservoir is
  1. 2gh
  2. C.V. 2gh
  3. Cd 2gh
  4. Cc 2gh

Answer:B

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95. For the free settling of a spherical particle through a fluid, the slope of, CD-log NRe , plot is
  1. 1
  2. -1
  3. 0.5
  4. -0.5

Answer:B

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96. A centrifugal pump loses prime after starting. The reason of this trouble may be
  1. incomplete priming.
  2. too high a suction lift.
  3. low available NPSH and air leaks in the suction pipe.
  4. all (a), (b), and (c).

Answer:D

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97. A jet strikes a curved plate at its ______
  1. Sides
  2. Surface
  3. Centre
  4. Does not strike

Answer:C

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98. Venturimeter and orificemeter measures the __________ of the fluid.
  1. Pressure
  2. maximum velocity
  3. average velocity
  4. point velocity

Answer:C

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99. Surge tanks are provided in high pressure water pipelines to
  1. store a definte quantity ofwater all the time
  2. reduce the water hammer
  3. facilitate easy dismantling of pipeline for cleaning and maintenance.
  4. none of these.

Answer:B

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100. Working principle of manometer comprises of balancing a column of liquid against the pressure to be measured. Which pressure is measured by inclined tube manometer
  1. small differential
  2. Atmospheric
  3. Absolute
  4. Gage

Answer:A

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101. Isotropic turbulence occurs
  1. where there is no velocity gradient.
  2. at higher temperatures.
  3. only in Newtonion fluids.
  4. none of these.

Answer:A

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102. The co-efficient of drag and lift for an incompressible fluid depends on the
  1. Reynolds number
  2. Froude number
  3. Mach number
  4. all (a), (b) and (c)

Answer:A

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103. Which one of the following is the dimension of specific volume of a liquid?
  1. [M1 L-3 T0].
  2. [M-1 L3 T0].
  3. [M-1 L-3 T0].
  4. [M0 L3 T0].

Answer:B

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104. Euler's equation of motion states, that at every point, the
  1. fluid momentum is constant.
  2. force per unit mass equals acceleration.
  3. rate of mass outflow is equal to the rate of mass inflow.
  4. none of these.

Answer:B

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105. Navier Stokes equation is used in law of conservation of
  1. Mass
  2. Energy
  3. both (a) & (b)
  4. Momentum

Answer:D

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106. Hydraulic intensifier is used for increasing the
  1. rate of velocity of liquid supply.
  2. momentum rate through delivery pipe.
  3. intensity of pressure of the liquid.
  4. momentum rate through delivery pipe.

Answer:C

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107. Hydrometer measures the specific gravity of liquids based on the principles of buoyancy. Pycnometer is used to measure the specific gravity of
  1. powder & grannular solids
  2. liquids
  3. low melting point semi-solids
  4. all 'a', 'b' & 'c'

Answer:D

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108. Euler's equation of motion is a statement expressing
  1. conservation of mass.
  2. conservation of energy.
  3. Newton's first law of motion.
  4. Newton's second law of motion.

Answer:A

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109. During ageing of fluid carrying pipes, the
  1. pipe becomes smoother with use.
  2. friction factor increases linearly with time.
  3. absolute roughness decreases with time.
  4. absolute roughness increases linearly with time.

Answer:D

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110. Pick out the wrong statement.
  1. The form drag is dependent upon the occurrence of a wake.
  2. The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance.
  3. An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity.
  4. Existence of the boundary layer in fluid flow is because of viscosity of the fluid.

Answer:C

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111. Mass velocity is independent of temperature & pressure, when the flow is
  1. unsteady through unchanged cross-section.
  2. steady through changing cross-section.
  3. steady and the cross-section is unchanged.
  4. unsteady and the cross-section is changed.

Answer:C

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112. Very small pressure difference (< 5 mm water coloumn) can be most conveniently measured by a/an __________ manometer.
  1. U-tube water.
  2. U-tube mercury.
  3. inclined tube mercury.
  4. inclined tube water.

Answer:D

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113. For a given Reynold number as d/D for an orifice increases, Cd will (where, d & D are orifice & pipe diameters respectively).
  1. increase
  2. decrease
  3. remain constant
  4. either (a) or (b); depends on other factors

Answer:A

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114. A differential pressure cell is used for
  1. measuring small pressure difference in gases.
  2. measuring small pressure difference in liquids.
  3. remote recording of pressure difference.
  4. measuring the difference of the impact & the static pressure.

Answer:C

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115. Which one of the following is the unit of specific weight?
  1. N = m3
  2. N = m 2
  3. N = m
  4. N = ms

Answer:A

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116. If more than two branches of pipes are to be connected at the same point, then use a/an
  1. elbow
  2. union
  3. tee
  4. none of these.

Answer:C

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117. In case of a centrifugal pump, the ratio of total delivered pressure to pressure developed with the impeller is called the __________ efficiency.
  1. manometric
  2. mechanical
  3. volumetric
  4. overall

Answer:A

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118. Acceleration head in a reciprocating pump
  1. increases the work done during delivery stroke.
  2. decreases the work done during suction stroke.
  3. does not change the work requirement of the pump.
  4. increases the work done during suction stroke.

Answer:C

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119. The ratio of inertial forces to elastic forces is called the __________ number.
  1. Reynolds
  2. Mach
  3. Euler
  4. Weber

Answer:B

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120. The value of the viscosity of an ideal fluid is
  1. zero
  2. unity
  3. infinity
  4. more than that of a real fluid

Answer:A

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121. Which one of the following is the unit of mass density?
  1. kg = m3
  2. kg = m2
  3. kg = m
  4. kg = ms

Answer:A

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122. Fluid flow at increasing rate through a diverging pipe is an example of __________ flow.
  1. steady uniform
  2. non-steady uniform
  3. steady non-uniform
  4. non-steady non-uniform

Answer:D

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123. The temperature in isentropic flow
  1. does not depend on Mach number.
  2. depends on Mach number only.
  3. cannot drop and then increase again downstream.
  4. none of these.

Answer:B

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124. If there is bucket full of oil and bucket full of water and you are asked to lift them, which one of the two will require more effort given that volume of buckets remains same?
  1. Oil bucket
  2. Water bucket
  3. Equal effort will be required to lift both of them
  4. None of the mentioned

Answer:B

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125. A fluid element has a velocity V = -y2 . xi + 2yx2 . j. The motion at (x, y) = (l/2, 1) is
  1. rotational and incompressible
  2. rotational and compressible
  3. irrotational and compressible
  4. irrotational and incompressible

Answer:B

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126. Drag force acting on a body does not depend upon the
  1. density of the fluid.
  2. density of the body.
  3. velocity of the body
  4. projected area of the body.

Answer:B

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127. Centrifugal pump is normally classified on the basis of the
  1. rpm
  2. type of casing.
  3. impeller blade angle.
  4. number of blades in impeller.

Answer:B

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128. Where does the maximum stress occur in case of laminar flow of incompressible fluid in a closed conduit of diameter 'd'?
  1. At the centre
  2. At d/4 from the wall
  3. At the wall
  4. At d/8 from the wall

Answer:C

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129. In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where, T = absolute temperature )
  1. 1/T
  2. T/1
  3. 1
  4. T

Answer:B

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130. Check valves are used
  1. at high pressure.
  2. in bends.
  3. for controlling water flow.
  4. for unidirectional flow.

Answer:D

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131. Velocity distribution for flow between two fixed parallel plates
  1. varies parabolically across the section.
  2. is constant over the entire cross-section.
  3. is zero at the plates and increases linearly to the midplane.
  4. none of these

Answer:A

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132. Priming is needed in a __________ pump.
132. Priming is needed in a __________ pump.
  1. reciprocating
  2. gear
  3. centrifugal
  4. diaphragm

Answer:C

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133. An ideal nozzle design aims at
  1. minimising wall friction.
  2. suppressing boundary layer separation.
  3. both (a) & (b).
  4. neither (a) nor (b).

Answer:C

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134. Which of the fluid forces are not considered in the Reynold's equation of flow ?
  1. Viscous forces
  2. Turbulent forces
  3. Pressure forces
  4. Compressibility forces

Answer:D

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135. For ideally incompressible fluid, the Mach number will be
  1. 1.5
  2. 1
  3. 0
  4. 5

Answer:B

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136. A mono pump is a __________ pump.
  1. centrifugal
  2. piston
  3. positive acting rotary
  4. a group of vacuum

Answer:C

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137. Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of __________ flow type.
  1. axial
  2. radial
  3. mixed
  4. none of these

Answer:A

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138. The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are P. Inlet pressure
Q. Compressor rpm
R. Delivery pressure
S. Volumetric flow rate at inlet.
  1. P, Q and R
  2. P and R
  3. R and S
  4. P, Rand S

Answer:A

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139. An ideal fluid is
  1. non-viscous
  2. incompressible
  3. both (a) & (b)
  4. neither (a) & (b)

Answer:C

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140. In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where M = molecular weight of the gas)
  1. 1/M
  2. M
  3. M/1
  4. 1

Answer:A

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141. Boundary layer separation is caused by the
  1. reduction of pressure to vapour pressure.
  2. boundary layer thickness reducing to zero.
  3. adverse pressure gradient.
  4. reduction of pressure gradient to zero.

Answer:D

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142. With increase in temperature, the vapor pressure of liquids
  1. increases
  2. increases linearly
  3. decreases
  4. remains constant

Answer:A

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143. The ratio of wall drag to total drag in the Stoke's law range is
  1. 0.5
  2. 1
  3. 1/3
  4. 2/3

Answer:D

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144. Rotary vacuum pumps can reduce the absolute pressure to as low as __________ mm Hg.
  1. 1
  2. 0.1
  3. 0.01
  4. 0.001

Answer:C

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145. A pitched-blade turbine draws __________ a straight blade turbine.
  1. less power than
  2. more power than
  3. same power as
  4. data insufficient to predict

Answer:A

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146. The most suitable flow measuring device for the fluid flow measurement in a very large diameter pipeline is a
  1. weir
  2. pitot tube
  3. Kennison nozzle
  4. V-notch

Answer:B

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147. A centrifugal pump is called a turbine pump, if it is having a
  1. turbine type impeller.
  2. vaned diffusion casing.
  3. rotating vaned volute.
  4. none of these.

Answer:B

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148. Remote control valve is a __________ valve.
  1. gate
  2. butterfly
  3. needle
  4. globe

Answer:B

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149. Calculate the specific weight and weight of 20dm3 of petrol of specific gravity 0.6.
  1. 5886,117.2
  2. 5886,234.2
  3. 11772,117.2
  4. None of the mentioned

Answer:A

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150. Which of the following quantities are computed by using the hydraulic radius for non-circular ducts ?
  1. Velocity and relative roughness.
  2. Head loss and velocity.
  3. Reynold number, relative roughness and head loss.
  4. Reynolds number and friction factor.

Answer:C

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151. Centre of pressure in an immersed body is __________ the centre of gravity.
  1. above
  2. below
  3. at
  4. either above or below; depends on the liquid density

Answer:B

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152. The centre of pressure is
  1. always below the centroid of the area.
  2. always above the centroid of the area.
  3. a point on the line of action of the resultant force.
  4. at the centroid of the submerged area.

Answer:C

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153. The uniformity of a gas fluidised bed depends upon the __________ of the solid particles.
  1. size
  2. surface properties
  3. both (a) and (b)
  4. neither (a) nor (b)

Answer:C

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154. Pascal law is not applicable for a/an __________ fluid.
  1. accelerating frictionless
  2. static
  3. uniformly moving
  4. none of these

Answer:D

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155. In a fluidised bed reactor
  1. temperature gradients are very high.
  2. temperature is more or less uniform.
  3. hot spots are formed.
  4. segregation of the solids occurs.

Answer:B

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156. A beaker is filled with a liquid up to the mark of one litre and weighed. The weight of the liquid is found to be 6.5 N. The specific weight of the liquid will be
  1. 6:5 kN = m3
  2. 6:6 kN = m3
  3. 6:7 kN = m3
  4. 6:8 kN = m3

Answer:A

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157. The flow of a liquid through tapering pipe at a constant rate is an example of __________ flow.
  1. steady uniform
  2. steady non uniform
  3. unsteady uniform
  4. unsteady non uniform

Answer:B

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158. A perfect gas
  1. does not satisfy PV = nRT.
  2. is incompressible and has zero viscosity.
  3. has constant specific heat.
  4. can't develop shear stresses.

Answer:C

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159. In a/an __________ , the flow rate of fluids is obtained by measuring the difference between the impact and the static pressure.
  1. rotameter
  2. pitot tube
  3. venturimeter
  4. flow nozzle

Answer:B

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160. Speed of sound in an ideal gas depends on its
  1. temperature
  2. pressure
  3. specific volume
  4. none of these

Answer:A

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161. If 200m3 of fluid has a weight of 1060N measured on the planet having acceleration due to gravity 6.625m/s2, what will be it’s specific volume?
  1. 0.8
  2. 0.7
  3. 0.9
  4. 0.5

Answer:A

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162. A centrifugal pump designed for handling water (μ = 1 cp) will deliver __________ when pumping a thicker oil (μ = 30 cp).
  1. less head & capacity
  2. more head
  3. more capacity
  4. less head & more capacity

Answer:A

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163. If 'x' is the depth of flow in an open channel of large width, then the hydraulic radius is equal to
  1. x
  2. x/2
  3. x/3
  4. 2x/3

Answer:A

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164. In fluid flow, the boundary layer separation can not occur
  1. in case of boundaries experiencing form drag.
  2. at points of abrupt changes in the flow directions.
  3. in laminar flow.
  4. none of these.

Answer:D

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165. For a given fluid flow rate, which of the following incurs maximum head loss ?
  1. Orifice meter
  2. Venturimeter
  3. Flow nozzle
  4. All of them incur the same head loss

Answer:A

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166. Which of the following assumptions enables the Euler's equation of motion to be integrated ?
  1. The fluid is incompressible
  2. The fluid is non-viscous.
  3. The continuity equation is satisfied.
  4. The flow is rotational and incompressible.

Answer:A

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167. Which among the following is the formula for Force when it strikes the plate?
  1. pav2
  2. pav
  3. pa
  4. maE

Answer:A

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168. A fluid whose apparent viscosity increases with shear rate is termed as the __________ fluid.
  1. Newtonion
  2. viscous
  3. dilatant
  4. non-viscous

Answer:C

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169. Which of the following is the most common pump for pumping either raw sewage or sludge ?
  1. Electromagnetic pump
  2. Centrifugal pump
  3. Reciprocating pump
  4. Gear pump

Answer:C

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170. Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter
  1. 5
  2. 50
  3. 500
  4. 1000

Answer:B

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171. For turbulent flow of an incompressible fluid through a pipe, the flow rate Q is proportional to (Δ P)n, where ΔP is the pressure drop. The value of exponent 'n' is
  1. 1
  2. 0
  3. < 1
  4. > 1

Answer:C

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172. Reciprocating pumps are not able to compete with the centrifugal pump for industrial use, mainly because these pumps have
  1. very low speeds.
  2. smaller discharge.
  3. higher capital &maintenance cost.
  4. high vibrations.

Answer:C

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173. To derive pav2, we take final velocity minus the initial velocity.
  1. True
  2. False

Answer:B

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174. Which of the following pipe bends will incur the largest head loss ?
  1. U-bend
  2. 30° bend
  3. 45° bend
  4. 90° bend

Answer:A

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175. Which is the most efficient and best for measuring very small flow rate of gases ?
  1. Venturimeter
  2. Orifice meter
  3. Rotameter
  4. Flow nozzle

Answer:C

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176. When the water is warm, the height to which it can be lifted by a pump
  1. decreases due to reduced viscosity.
  2. decreases due to reduced vapour pressure.
  3. increases due to increased vapour pressure
  4. decreases due to increased frictional resistance.

Answer:B

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177. Specific gravity is what kind of property?
  1. Intensive
  2. Extensive
  3. None of the mentioned
  4. It depends on external conditions

Answer:A

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178. Pipes having diameter 14 inches or more are designated by their
  1. outside diameter
  2. inside diameter
  3. schedule number
  4. none of these

Answer:A

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179. Viscosity of water at 40°C lies in the range of
  1. 1 x 10-3 to 2 x 10-3 kg/m.s
  2. 0.5 x 10-3 to 1 x 10-3 kg/m.s
  3. 1 to 2 kg/m.s
  4. 0.5 to 1 kg/m.s

Answer:B

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180. A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, the new discharge will be __________ litres/minute.
  1. 500
  2. 200
  3. 1000
  4. 750

Answer:A

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181. An compressible fluid’s specific gravity was measured on earth, on a planet having acceleration due to gravity 5.5 times that of earth, and in space at STP. Where will it be having highest value?
  1. on the earth
  2. on the planet
  3. in the space
  4. it will be constant everywhere

Answer:D

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182. The dimension of kinematic viscosity is
  1. ML-2T-1
  2. L2T-1
  3. ML-2T-2
  4. none of these

Answer:B

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183. A pipe of I.D. 4 m is bifurcated into two pipes of I.D. 2 m each. If the average velocity of water flowing through the main pipe is 5 m/sec, the average velocity through the bifurcated pipes is
  1. 20 m/sec
  2. 10 m/sec
  3. 52 m/sec
  4. 5 m/sec

Answer:B

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184. Turbulent flow generally occurs for cases involving
  1. highly viscous fluid
  2. very narrow passages
  3. very slow motion
  4. none of these

Answer:D

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185. Lower BWG means __________ of the tube.
  1. lower thickness
  2. lower cross-section
  3. outer diameter
  4. inner diameter

Answer:B

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186. For laminar flow of Newtonion fluid in a circular pipe, the velocity distribution is a function of the distance 'd' measured from the centre line of the pipe, and it follows a __________ relationship.
  1. logarithmic
  2. parabolic
  3. hyperbolic
  4. linear

Answer:B

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187. Which among the following is a formula for force when it acts perpendicular to the direction of flow?
  1. pav2 SinθCosθ
  2. pav Sin2θ
  3. pa Sin2θ
  4. maE Sin2θ

Answer:A

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188. The Prandtl mixing length is
  1. zero at the pipe wall and is a universal constant.
  2. independent of radial distance from the pipe axis.
  3. independent of the shear stress.
  4. useful for computing laminar flow problems.

Answer:D

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189. N2Re/NFr is called the __________ number.
  1. Brinkman
  2. Galileo
  3. Archimedes
  4. Euler

Answer:B

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190. As the velocity V and thus the Reynolds number of a flow past a sphere increases from very low value, the drag force for Re << 1
  1. increases linearly with V.
  2. decreases linearly with V.
  3. decreases as V2.
  4. none of these.

Answer:A

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191. Self-priming centrifugal pump can be used for
  1. booster service.
  2. pumping liquid fertilisers (e.g. liquid NH3).
  3. pumping industrial wastes.
  4. all (a), (b) and (c).

Answer:D

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192. Water hammer is caused, when water flowing in a pipe is suddenly brought to rest by closing the valve. The extent of pressure thus produced due to water hammer depends on the
  1. pipe length
  2. fluid velocity in the pipe
  3. time taken to close the valve
  4. all (a), (b) and (c)

Answer:D

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193. Bernoull's equation does not apply to the functioning of a/an
  1. venturimeter
  2. orificem
  3. pitot tube
  4. none of these

Answer:D

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194. What is the shear rate at the pipe wall, in case of laminar flow of Newtonion fluids in a pipe of diameter 'D' & length 'L' incurring a pressure drop 'Δp' with average velocity 'Vavg'?
  1. D Δp/8L
  2. D Δp/4L
  3. 8 . Vavg/D
  4. 4 . Vavg/D

Answer:C

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195. Pascal's law is valid, only when the fluid is
  1. frictionless and at rest.
  2. at rest.
  3. at rest and when the frictionless fluid is in motion.
  4. none of these.

Answer:B

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196. The pressure head of a flow meter remains constant for
  1. venturimeter
  2. orificemeter
  3. rotameter
  4. pitot tube

Answer:C

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197. A venturimeter can not be used for the direct measurement of
  1. datum difference in the stretch of pipeflow
  2. pressure difference in the flow throughpipeline.
  3. friction loss in pipe flow.
  4. all (a), (b) and (c)

Answer:D

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198. A double acting reciprocating pump compared to a single acting pump (of almost same size working under same pressure levels) would give almost double
  1. head
  2. discharge
  3. efficiency
  4. none of these

Answer:B

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199. Which of the following is used for very accurate measurement of flow of gas at low velocity ?
  1. Pitot tube
  2. Rotameter
  3. Segmental orificemeter
  4. Hot wire annemometer

Answer:D

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200. The rate of shear versus the shear stress curves are time dependent for __________ fluid.
  1. thixotropic
  2. rheopectic
  3. both (a) & (b)
  4. neither (a) nor (b)

Answer:C

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201. In Newton's law range, the drag co-efficient for the motion of spherical particle in a stationary fluid is
  1. 0.44
  2. 0.044
  3. 4.4
  4. 44

Answer:A

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202. The velocity component after striking the surface will be________
  1. One
  2. Zero
  3. Infinity
  4. Negative

Answer:B

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203. A pressure of 10 m head of water is equivalent to __________ kN/m2.
  1. 98
  2. 147
  3. 196
  4. 49

Answer:A

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204. A pressure head of 320 metres of water in meters of CCl4 (sp.gr = 1.6) will be
  1. 100
  2. 200
  3. 320
  4. 160

Answer:B

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205. The ratio of the wall drag to the form drag in the Stoke's law range (for motion of spherical particles in a stationary fluid) is
  1. 0.5
  2. 1
  3. 2
  4. 0.33

Answer:C

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206. For turbulent flow in smooth circular pipe, the velocity distribution is a function of the distance 'd' measured from the wall of the pipe and the friction velocity 'v', and it follows a __________ relationship.
  1. logarithmic
  2. linear
  3. hyperbolic
  4. parabolic

Answer:A

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207. Maintenance cost of a __________ pump for a particular duty is the least.
  1. centrifugal
  2. reciprocating
  3. volute
  4. gear

Answer:A

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208. Choking in case of pipe flow means that a
  1. specified mass flow rate can not be achieved.
  2. valve is closed in the line.
  3. restriction in flow cross-section area occurs.
  4. none of these

Answer:A

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209. Velocity of liquid hydrocarbon fuels in a pipeline can not be measured by magnetic flowmeters, because their __________ is very low/small.
  1. thermal conductivity
  2. electrical conductivity
  3. specific gravity
  4. electrical resistivity

Answer:B

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210. The nominal size of a hose pipe is specified by its
  1. I.D.
  2. O.D.
  3. thickness
  4. none of these

Answer:A

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211. At what angle does the jet deflect after striking a stationery vertical plate?
  1. 30
  2. 60
  3. 90
  4. 0

Answer:C

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212. Transition from laminar flow to turbulent flow is aided by the
  1. surface roughness and curvature (i.e.sharp corners).
  2. vibration.
  3. pressure gradient and the compressibility of the flowing medium.
  4. all (a), (b) & (c).

Answer:D

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213. For flow of fluids through packed bed, the superficial velocity is
  1. less than the average velocity through channels.
  2. more than the average velocity through channels.
  3. dependent on the pressure drop across the bed.
  4. same as the average velocity through channels.

Answer:A

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214. Cd is always __________ Cc.
  1. greater than
  2. less than
  3. equal to
  4. either more or less than

Answer:A

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215. Which of the following is an undesirable property of a manometric liquid ?
  1. Non-sticky & non-corrosive nature.
  2. High vapour pressure.
  3. Low viscosity & surface tension.
  4. Low co-efficient of thermal expansion.

Answer:B

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216. Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head.
  1. manometric
  2. total
  3. static
  4. friction

Answer:A

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217. In a stationery vertical plate, the jet after striking the plate will move _______
  1. In opposite direction
  2. Along the plate
  3. Perpendicular to the plate
  4. Parallel to the plate

Answer:B

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218. The speed of sound in an ideal gas varies as the
  1. temperature
  2. pressure
  3. density
  4. none of these

Answer:A

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219. The maximum head that can be developed by a single impeller is __________ ft.
  1. 25
  2. 100
  3. 250-300
  4. 1000

Answer:C

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220. The general relationship between speed N, head H, power P and discharge Q for a centrifugal pump is
  1. Q∝N : H∝N2 : P∝N3
  2. Q∝N2 : H∝N3 : P∝N
  3. Q∝N : H∝N3 : P∝N2
  4. Q∝N3 : H∝N : P∝N2

Answer:A

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221. What is the ratio of the velocity at the axis of the pipe to the mean velocity of flow in case of pipe flow under viscous condition ?
  1. 0.5
  2. 0.67
  3. 1
  4. 2

Answer:D

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222. Foot valve provided in the pump is a __________ valve.
  1. direction control
  2. back pressure
  3. relief
  4. pressure reduction

Answer:B

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223. Force exerted by a jet on a moving plate happens in how many cases?
  1. 3 cases
  2. 2 cases
  3. 1 case
  4. Nil

Answer:A

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224. The discharge co-efficient for an orificemeter does not depend upon the
  1. pipe length.
  2. ratio of pipe diameter to orifice diameter
  3. type of orifice & the Reynolds number.
  4. pipe diameter.

Answer:A

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225. Which of the following options will facilitate the achievement of a very high head (say 30 metres) in case of a centrifugal pump?
  1. Increasing the impeller speed and the volute area.
  2. Increasing the number of vanes in the impeller.
  3. Mounting of two or more impellers in series on a single shaft.
  4. Either of (a), (b) or (c).

Answer:C

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226 .An equipotential line is __________ to the velocity vector at every point.
  1. normal
  2. Perpendicular
  3. tangential
  4. none of these

Answer:A

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227. Path followed by water jet issuing from the bottom of a water tank will be a
  1. parabola (vertex being at the opening).
  2. hyperbola
  3. horizontal straight line.
  4. zig-zag path (which is geometrically undefined).

Answer:A

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228. Which of the following produces maximum pressure difference for transportation of gases ?
  1. Vaccum pumps
  2. Blowers
  3. Fans
  4. Compressors

Answer:D

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230. Drag co-efficient in hindered settling is __________ that in free settling.
  1. less than
  2. equal to
  3. not necessarily greater than
  4. always greater than

Answer:D

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231. Efficiency of power transmission (η) through a circular pipe is given by (ht - hf)/ht, which has a maximum value of __________ percent.
  1. 33:3
  2. 50
  3. 66.6
  4. 88.8

Answer:C

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232. One dimensional fluid flow implies the
  1. flow in straight lines only.
  2. uniform flow.
  3. steady uniform flow.
  4. flow in which transverse components are zero.

Answer:D

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233. __________ forces act on a particle moving through a stationary fluid.
  1. Gravity
  2. Drag
  3. Buoyant
  4. all (a), (b), & (c)

Answer:D

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234. Hydraulic radius is the ratio of
  1. wetted perimeter to flow area.
  2. flow area to wetted perimeter.
  3. flow area to square of wetted perimeter.
  4. square root of flow area to wetted perimeter

Answer:B

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235. The unit of bulk modulus of elasticity for a liquid in S.I. unit is
  1. N
  2. N/m
  3. N/m2
  4. N/m3

Answer:C

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236. Power requirement of fans having constant wheel diameter varies __________ fan speed.
  1. as square of
  2. directly as
  3. as cube of
  4. none of these

Answer:C

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237. In the low Reynolds number region, the drag force on a sphere is proportional to
  1. V
  2. V2
  3. V4
  4. V0.5

Answer:A

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v238. The continuity equation
  1. is independent of the compressibility of the fluid.
  2. is dependent upon the viscosity of the fluid
  3. represents the conservation of mass.
  4. none of these.

Answer:C

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239. The value of the Bulk Modulus of an ideal fluid is
  1. zero
  2. unity
  3. infinity
  4. less than that of a real fluid

Answer:C

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240. Experimental study of laminar fluid flow through a circular tube was conducted by
  1. Reynolds
  2. Hagen and Poiseuille
  3. Pascal
  4. Blake-Plummer

Answer:B

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241. The most economical flow control valve for use with large diameter pipes is a
  1. butterfly valve
  2. globe valve
  3. needle valve
  4. none of these

Answer:A

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242. Each term in Bernaulli's equation represents the __________ of the fluid.
  1. energy per unit mass
  2. energy per unit weight
  3. force per unit mass
  4. none of these

Answer:B

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243. Which of the following is a dimensionless parameter ?
  1. Angular velocity
  2. Specific weight
  3. Kinematic viscosity
  4. None of these

Answer:D

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244. Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1. If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe, will
  1. increase.
  2. decrease.
  3. remain unchanged
  4. increase or decrease depending on the pipe material.

Answer:A

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245. Buoyant force
  1. for non-symmetrical bodies is not vertical.
  2. depends on the depth of the submergence of the floating body.
  3. depends on the weight of the floating body.
  4. none of these

Answer:C

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246. For the laminar flow of a fluid in a circular pipe of radius R, the Hagen-Poisseule equation predicts the volumetric flow rate to be proportional to
  1. R
  2. R2
  3. R4
  4. R0.5

Answer:C

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247. Interstage coolers are provided in a multistage compressor to
  1. save power in compressing a given volume to a given pressure.
  2. cool the delivered air.
  3. achieve the exact delivery pressure.
  4. none of these.

Answer:A

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248. Reynolds number is the ratio of
  1. viscous forces to gravity forces.
  2. inertial forces to viscous forces.
  3. viscous forces to inertial forces.
  4. inertial forces to gravity forces.

Answer:B

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249. The value of the compressibility of an ideal fluid is
  1. zero
  2. unity
  3. infinity
  4. more than that of a real fluid

Answer:A

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