Fluid Mechanics MCQs

Question 1

An isentropic process is the one, in which

Accepted Answer

pvr = constant, and process is reversible

Answer

pv = constant

Answer

pvr = constant

Answer

None of these

Question 2

Actual lift of a pump is always less than the theoretical lift and is limited by the

Accepted Answer

All of the above

Answer

Specific gravity & temperature of the liquid

Answer

Leakage & pressure decreasing at higher elevations

Answer

Frictional resistance through pipes, fittings & passages

Question 3

Which of the following can be used to create a flow of gas, where no significant compression is required?

Accepted Answer

Blower

Answer

Reciprocating compressor

Answer

Axial flow compressor

Answer

Centrifugal compressor

Question 4

Choking in case of pipe flow means that a

Accepted Answer

Specified mass flow rate can not be achieved

Answer

Valve is closed in the line

Answer

Restriction in flow cross-section area occurs

Answer

None of these

Question 5

Cavitation can be prevented by

Accepted Answer

Maintaining the suction head sufficiently greater than the vapour pressure

Answer

Suitably designing the pump

Answer

Maintaining suction head = developed head

Answer

Maintaining suction head lower than the vapour pressure

Question 6

The contraction co-efficient for Borda's mouthpiece (for frictionless fluid) is

Accepted Answer

0.5

Answer

0.1

Answer

0.94

Answer

1

Question 7

In case of venturimeters, friction losses are about __________ percent of maximum velocity head.

Accepted Answer

2

Answer

8

Answer

12

Answer

20

Question 8

Erosion and pits formation on the impeller of a centrifugal pump may be due to

Accepted Answer

Cavitation

Answer

Low speed of impeller

Answer

Its operation with delivery valve closed for considerable time after starting the pump

Answer

Off centering of pump with motor

Question 9

Check in a centrifugal pump is

Accepted Answer

All of the above

Answer

Provided in the discharge line

Answer

Generally a globe valve

Answer

Provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running