Fluid Mechanics MCQs

Question 1

A centrifugal pump loses prime after starting. The reason of this trouble may be

Accepted Answer

All of the above

Answer

Incomplete priming

Answer

Too high a suction lift

Answer

Low available NPSH and air leaks in the suction pipe

Question 2

For a specific centrifugal air blower operating at constant speed & capacity, the power requirement and pressure vary

Accepted Answer

Directly as gas density

Answer

Directly as square of gas density

Answer

Directly as square root of gas density

Answer

Inversely as gas density

Question 3

The range of a particular rotameter can be increased by

Accepted Answer

Use of floats of different densities

Answer

No means

Answer

Increasing the diameter of the float

Answer

Decreasing the diameter of the float

Question 4

Two liquids manometer is used for measuring small pressure differences in

Accepted Answer

Gases

Answer

Liquids

Answer

Mixture of hydrocarbons

Answer

None of these

Question 5

Pick out the wrong statement about a streamline.

Accepted Answer

Streamlines intersect at isolated point of zero velocity and infintie velocity

Answer

It is always parallel to the main direction of the fluid flow

Answer

It is a line across which there is no flow and it is equivalent to a rigid boundary

Answer

The fluid lying between any two streamlines can be considered to be in isolation and the streamline spacing varies inversely as the velocity

Question 6

When larger particles e.g., grains are subjected to fluidisation, the corresponding bed produced is termed as the __________ bed.

Accepted Answer

Spouted

Answer

Sluggish

Answer

Boiling

Answer

Teeter

Question 7

Co-efficient of velocity is __________ the coefficient of discharge.

Accepted Answer

More than

Answer

Less than

Answer

Equal to

Answer

Not related to

Question 8

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

Accepted Answer

Both A & B

Answer

Flow rate

Answer

Mean velocity

Answer

Neither A nor B

Question 9

Which of the following has the minimum compressibility?

Accepted Answer

Water at room temperature

Answer

Air at room temperature

Answer

Oxygen at room temperature

Answer

Nitrogen at room temperature