Fluid Mechanics MCQs

Question 1

For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor.

Accepted Answer

Brings about no further reduction of

Answer

Increases

Answer

Decreases

Answer

None of these

Question 2

Mach number is important in a fluid flow problem, when the inertia and __________ forces predominate.

Accepted Answer

Elastic

Answer

Viscous

Answer

Gravity

Answer

None of these

Question 3

In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where M = molecular weight of the gas)

Accepted Answer

$$\frac{1}{{\sqrt {	ext{M}} }}$$

Answer

$$\sqrt {	ext{M}} $$

Answer

$$\frac{1}{{	ext{M}}}$$

Answer

M

Question 4

Fanning friction factor is equal to (where, fB = Blassius friction factor).

Accepted Answer

$$\frac{{{{	ext{f}}_{	ext{B}}}}}{4}$$

Answer

$$\frac{{{{	ext{f}}_{	ext{B}}}}}{2}$$

Answer

4fB

Answer

2fB

Question 5

For the free settling of a spherical particle through a fluid, the slope of, CD-log NRe , plot is

Accepted Answer

-1

Answer

1

Answer

0.5

Answer

-0.5

Question 6

Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency)

Accepted Answer

ηm = ηv × ηma

Answer

ηma × ηm × ηv = ηo

Answer

ηma = ηm × ηv

Answer

ηv = ηm × ηma

Question 7

f = 16/NRe, is valid for

Accepted Answer

None of these

Answer

Turbulent flow

Answer

Laminar flow through an open channel

Answer

Steady flow

Question 8

A fluid is a substance, that

Accepted Answer

Flows when even a small shear is applied to it

Answer

Has to be kept in a closed container

Answer

Is almost incompressible

Answer

Has zero shear stress

Question 9

A fluid is the one, which

Accepted Answer

Cannot remain at rest under the action of shear force

Answer

Continuously expands till it fills any container

Answer

Is incompressible

Answer

Permanently resists distortion