Fluid Mechanics Mcqs for Chemical - Set 10

1)   Shear stress in a fluid flowing in a round pipe_________________?

a. Varies parabolically across the cross-section
b. Remains constant over the cross-section
c. Is zero at the centre and varies linearly with the radius
d. Is zero at the wall and increases linearly to the centre
Answer  Explanation 

ANSWER: Is zero at the centre and varies linearly with the radius

Explanation:
No explanation is available for this question!


2)   Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, ζ = surface tension of mercury)____________________?

a. d
b. 1/d
c. ζ
d. 1/ζ
Answer  Explanation 

ANSWER: ζ

Explanation:
No explanation is available for this question!


3)   Hydraulic mean depth (Dm) for a circular pipe of diameter ‘D’ flowing full is 0.25 D. For a circular channel, at Dm = 0.3 D, gives the condition for the maximum ?

a. Flow rate
b. Mean velocity
c. Both ‘a’ & ‘b’
d. Neither ‘a’ nor ‘
Answer  Explanation 

ANSWER: Mean velocity

Explanation:
No explanation is available for this question!


4)   A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m3 ) is to be fluidised by water (density 1000 kg/m3 ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is________________?

a. 4.4 KPa
b. 2.94 KPa
c. 3.7 KPa
d. None of these
Answer  Explanation 

ANSWER: 4.4 KPa

Explanation:
No explanation is available for this question!


5)   Which of the following denotes the effect of compressibility in fluid flow ?

a. Weber number
b. Mach number
c. Euler number
d. Reynolds number
Answer  Explanation 

ANSWER: Mach number

Explanation:
No explanation is available for this question!


6)   Reynolds number for water flow through a tube of I.D. 5 cm is 1500. If a liquid of 5 centipoise viscosity and 0.8 specific gravity flows in the same pipe at the same velocity, then the pressure drop will______________________?

a. Increase
b. Decrease
c. Remain same
d. Data insufficient to predict pressure drop
Answer  Explanation 

ANSWER: Increase

Explanation:
No explanation is available for this question!


7)   The ratio of the depth of flow to the hydraulic radius for the most economical trapezoidal section, in open channel flow is_____________________?

a. 0.5
b. 1
c. 1.5
d. 2
Answer  Explanation 

ANSWER: 2

Explanation:
No explanation is available for this question!


8)   Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (ε0) with age/time (t) (where, ε = roughness of the surface after time’t’. α = a co-efficient to be experimentally determined) ?

a. ε = ε0 + α.t
b. ε = ε0 + α.t2
c. ε = ε0 + α.t3
d. ε = ε0 + α.t4
Answer  Explanation 

ANSWER: ε = ε0 + α.t

Explanation:
No explanation is available for this question!


9)   ______________ pumps are axial flow pumps?

a. Turbine
b. Propeller
c. Diffuser
d. None of these
Answer  Explanation 

ANSWER: Propeller

Explanation:
No explanation is available for this question!


10)   In a fully turbulent flow (Re > 105) in a pipe of diameter ‘d’, for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is_______________?

a. d
b. d2
c. d2.5
d. d4
Answer  Explanation 

ANSWER: d2.5

Explanation:
No explanation is available for this question!


11)   For a particle settling in water at its terminal settling velocity, which of the following is true ?

a. Buoyancy = weight + drag
b. Weight = buoyancy + drag
c. Drag = buoyancy + weight
d. Drag = weight
Answer  Explanation 

ANSWER: Weight = buoyancy + drag

Explanation:
No explanation is available for this question!


12)   Gear pump_________________?

a. Is a positive displacement pump
b. Is a centrifugal pump
c. Is a non-positive displacement pump
d. Can be started with delivery valve closed
Answer  Explanation 

ANSWER: Is a positive displacement pump

Explanation:
No explanation is available for this question!


13)   Most commonly used joint in the underground pipe lines is the________________?

a. Sleeve joint
b. Coupling
c. Flange
d. Expansion joint
Answer  Explanation 

ANSWER: Sleeve joint

Explanation:
No explanation is available for this question!


14)   Ratio of pressure and inertia force gives ______________ number?

a. Weber
b. Mach
c. Euler
d. Froude
Answer  Explanation 

ANSWER: Euler

Explanation:
No explanation is available for this question!


15)   With increasing flow rate, the hydraulic efficiency of a centrifugal pump__________________?

a. Monotonically decreases
b. Decreases and then increases
c. Remains constant
d. Increases and then decreases
Answer  Explanation 

ANSWER: Monotonically decreases

Explanation:
No explanation is available for this question!


16)   Steady uniform flow is represented by flow through a/an ___________________?

a. Long pipe at constant rate
b. Long pipe at decreasing rate
c. Expanding tube at constant rate
d. None of these
Answer  Explanation 

ANSWER: Long pipe at constant rate

Explanation:
No explanation is available for this question!


17)   Which of the following is not a dimension-less parameter ?

a. Euler number
b. Specific gravity
c. Fanning friction factor
d. None of these
Answer  Explanation 

ANSWER: None of these

Explanation:
No explanation is available for this question!


18)   A fluid is the one, which___________________?

a. Cannot remain at rest under the action of shear force
b. Continuously expands till it fills any container
c. Is incompressible
d. Permanently resists distortion
Answer  Explanation 

ANSWER: Cannot remain at rest under the action of shear force

Explanation:
No explanation is available for this question!


19)   Brownian movement is prominent in the particle size range of _____________ microns in case of settling of a particle in a fluid?

a. 2 to 3
b. 0.01 to 0.10
c. 200 to 300
d. 100 to 1000
Answer  Explanation 

ANSWER: 2 to 3

Explanation:
No explanation is available for this question!


20)   The velocity profile for turbulent flow through a closed conduit is_______________?

a. Logarithmic
b. Parabolic
c. Hyperbolic
d. Linear
Answer  Explanation 

ANSWER: Logarithmic

Explanation:
No explanation is available for this question!


21)   Nominal size of a pipe is an indication of its ______________ diameter?

a. Inner
b. Outer
c. Approximate
d. None of these
Answer  Explanation 

ANSWER: Approximate

Explanation:
No explanation is available for this question!


22)   The fluid in which the shearing stress within it is proportional to the velocity gradient across the sheared section, is called a _____________ fluid?

a. Bingham
b. Newtonian
c. Perfect
d. None of these
Answer  Explanation 

ANSWER: Newtonian

Explanation:
No explanation is available for this question!


23)   With increase in pump speed, its NPSH requirement_________________?

a. Decreases
b. Increases
c. Remains unaltered
d. Can either increase or decrease; depends on other factors
Answer  Explanation 

ANSWER: Increases

Explanation:
No explanation is available for this question!


24)   Pressure drag does not depend upon the_________________?

a. Roughness of surface of the body
b. Pressure of main flow only
c. Length of the body in flow direction
d. All A., B. and C.
Answer  Explanation 

ANSWER: All A., B. and C.

Explanation:
No explanation is available for this question!


25)   The exit cone angle in case of a standard Venturimeter is _____________ the entrance cone angle?

a. Smaller than
b. Greater than
c. Equal to
d. Either A. or B.
Answer  Explanation 

ANSWER: Smaller than

Explanation:
No explanation is available for this question!


26)   Molten soap mass is transported by a ______________ pump?

a. Diaphragm
b. Reciprocating
c. Gear
d. Centrifugal
Answer  Explanation 

ANSWER: Centrifugal

Explanation:
No explanation is available for this question!


27)   Assuming flow to be laminar, if the diameter of the pipe is halved, then the pressure drop will_______________?

a. Increase
b. Decrease
c. Remain same
d. Be quadrupled
Answer  Explanation 

ANSWER: Increase

Explanation:
No explanation is available for this question!


28)   Dimension of surface tension is (where, F = force, L = length) ?

a. FL-1
b. F-1. L
c. F.L-2
d. F-2. L
Answer  Explanation 

ANSWER: FL-1

Explanation:
No explanation is available for this question!


29)   The schedule number of a pipe is an indication of its_________________?

a. Size
b. Roughness
c. Material density
d. Wall thickness
Answer  Explanation 

ANSWER: Wall thickness

Explanation:
No explanation is available for this question!


30)   A fluid is a substance, that_________________?

a. Has to be kept in a closed container
b. Is almost incompressible
c. Has zero shear stress
d. Flows when even a small shear is applied to it
Answer  Explanation 

ANSWER: Flows when even a small shear is applied to it

Explanation:
No explanation is available for this question!


31)   The continuity equation__________________?

a. Relates mass flow rate along a stream tube
b. Relates work and energy
c. Stipulates that Newton’s second law of motion must be satisfied at every point in the fluid
d. None of these
Answer  Explanation 

ANSWER: Relates mass flow rate along a stream tube

Explanation:
No explanation is available for this question!


32)   The flow of gas along a pipe in the direction of decreasing pressure causes decrease in its__________________?

a. Viscosity
b. Specific volume
c. Velocity
d. None of these
Answer  Explanation 

ANSWER: Specific volume

Explanation:
No explanation is available for this question!


33)   In case of supersonic flow of a fluid through pipeline, the ‘Mach number’ is__________________?

a. 0
b. 1
c. < 1
d. > 1
Answer  Explanation 

ANSWER: > 1

Explanation:
No explanation is available for this question!


34)   Gradually varied flow in open channel is a/an ____________ flow?

a. Steady uniform
b. Steady non-uniform
c. Unsteady uniform
d. Unsteady non-uniform
Answer  Explanation 

ANSWER: Steady non-uniform

Explanation:
No explanation is available for this question!


35)   Stoke’s law is valid, when NRe, p is less than_________________?

a. 2
b. 100
c. 2100
d. 700
Answer  Explanation 

ANSWER: 2

Explanation:
No explanation is available for this question!


36)   Cavitation in a centrifugal pump can be avoided by keeping the__________________?

a. Inlet pressure high
b. Outlet pressure low
c. Inlet pressure low
d. Outlet pressure high
Answer  Explanation 

ANSWER: Inlet pressure high

Explanation:
No explanation is available for this question!


37)   Momentum transfer in laminar flow of fluids results due to the_________________?

a. Viscosity
b. Density
c. Velocity gradient
d. None of these
Answer  Explanation 

ANSWER: Velocity gradient

Explanation:
No explanation is available for this question!


38)   What is the ratio of fluid carrying capacity of two pipes having diameters d1 and d2 respectively ?

a. (d1/d2)0.8
b. (d1/d2)0.5
c. d1/d2
d. (d1/d2)2
Answer  Explanation 

ANSWER: (d1/d2)0.5

Explanation:
No explanation is available for this question!


39)   Mach number is important in a fluid flow problem, when the inertia and _____________ forces predominate?

a. Elastic
b. Viscous
c. Gravity
d. None of these
Answer  Explanation 

ANSWER: Elastic

Explanation:
No explanation is available for this question!


40)   Boundary layer thickness in turbulent flow over a flat plate increases as(where, d = distance from the leading edge.) ?

a. √d
b. √d
c. d4/5
d. d1/3
Answer  Explanation 

ANSWER: d4/5

Explanation:
No explanation is available for this question!