81. The pressure and power requirement of a gas fan at constant speed & capacity varies __________ the gas density.
Directly as
Inversely as square root of
Inversely as
As square of
✅ The correct answer is option A.
Fluid Mechanics MCQs
82. Water hammer in a pipeline results from the
Bursting of pipelines due to closure by a valve
Rapid pressure change due to a rapid change in the rate of flow
Pressure increase due to closure of a valve resulting in decrease in rate of flow
None of these
✅ The correct answer is option B.
83. Hydraulic radius is the ratio of
Wetted perimeter to flow area
Flow area to wetted perimeter
Flow area to square of wetted perimeter
Square root of flow area to wetted perimeter
✅ The correct answer is option B.
84. A lubricant 100 times more viscous than water would have a viscosity (in Pa.s)
0.01
0.1
1
10
✅ The correct answer is option B.
85. The most serious disadvantage of an orificemeter is that
It is not very accurate
It is very costly
Most of the pressure drop is not recoverable
It is not suitable for measuring gas flow
✅ The correct answer is option C.
86. The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is
Parabolic
Flat
Flat near the wall and parabolic in the middle
Parabolic near the wall and flat in the middle
✅ The correct answer is option D.
87. For turbulent fluid flow in pipe, the expression for Prandtl one seventh power law is (where, r = pipe radius, x = distance).
V/Vmax = (x/r)1/7
V/Vmax = (r/x)1/7
V/Vmax = (x.r)1/7
None of these
✅ The correct answer is option A.
88. Viscosity of water at 40°C lies in the range of
1 x 10⁻³ to 2 x 10⁻³ kg/m.s
0.5 x 10⁻³ to 1 x 10⁻³ kg/m.s
1 to 2 kg/m.s
0.5 to 1 kg/m.s
✅ The correct answer is option B.
89. Drag co-efficient for motion of spherical particles in a stationary fluid in the stoke’s law range is
24/NRe,p
16/NRe,p
64/NRe,p
48/NRe,p
✅ The correct answer is option A.
90. The pressure head on sudden contraction in a horizontal pipe is converted into the __________ head.
Elevation
Velocity
Both A and B
Neither A nor B
✅ The correct answer is option B.