Fluid Mechanics MCQs

Question 1

Pick out the wrong statement.

Accepted Answer

An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity

Answer

The form drag is dependent upon the occurrence of a wake

Answer

The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance

Answer

Existence of the boundary layer in fluid flow is because of viscosity of the fluid

Question 2

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.

Accepted Answer

f1 > f2

Answer

f1 = f2

Answer

f1 < f2

Answer

Data not sufficient to relate f1 & f2

Question 3

In turbulent flow, a rough pipe has the same friction factor as a smooth pipe

Accepted Answer

When the roughness projections are much smaller than the thickness of the laminar film

Answer

In the zone of complete turbulence

Answer

Everywhere in the transition zone

Answer

When the friction factor is independent of the Reynold's number

Question 4

In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure __________ the vapor pressure of the liquid at the suction temperature.

Accepted Answer

Higher than

Answer

Lower than

Answer

Equal to

Answer

None of these

Question 5

Drag co-efficient for motion of spherical particles in a stationary fluid in the stoke's law range is

Accepted Answer

$$\frac{{24}}{{{{	ext{N}}_{{	ext{Re,p}}}}}}$$

Answer

$$\frac{{16}}{{{{	ext{N}}_{{	ext{Re,p}}}}}}$$

Answer

$$\frac{{64}}{{{{	ext{N}}_{{	ext{Re,p}}}}}}$$

Answer

$$\frac{{48}}{{{{	ext{N}}_{{	ext{Re,p}}}}}}$$

Question 6

Vena-contracta formed during flow of a liquid through an orificemeter has

Accepted Answer

Minimum liquid cross-section

Answer

More diameter compared to orifice diameter

Answer

Minimum velocity of fluid stream

Answer

None of these

Question 7

Hydraulic intensifier is used for increasing the

Accepted Answer

Intensity of pressure of the liquid

Answer

Rate of velocity of liquid supply

Answer

Rate of flow through delivery pipeline of a pump

Answer

Momentum rate through delivery pipe

Question 8

In case of end to end connection of two or more pipes in series, the __________ each pipe.

Accepted Answer

Same rate of flow passes through

Answer

Head loss is same through

Answer

Rate of flow in each pipe is proportional to the length of

Answer

Total flow rate is the sum of flow rate in

Question 9

For the manometer set up shown in the figure, the pressure difference PA - PB is given by

Accepted Answer

(ρH - ρair)gH

Answer

(ρH - ρL)gH

Answer

(ρH - ρL) gH + (ρL - ρair) . g(L - H)

Answer

(ρH - ρL) gL + (ρL - ρair)gH