Fluid Mechanics - GATE practice papers - Mechanical

1)   Which among the following sentences are true for turbulent flow

(1) The frictional resistance is proportional to the square of the velocity
(2) The frictional resistance is independent of the pressure
(3) The frictional resistance is proportional to the density of fluid
(4) The frictional resistance slightly varies with temperature (Marks: 02)

- Published on 19 Oct 15

a. sentences (1), (2) and (3) are correct
b. sentences (2), (3) and (4) are correct
c. sentences (1), (2) and (4) are correct
d. all the sentences are correct
Answer  Explanation 

ANSWER: all the sentences are correct

Explanation:
The laws of friction for turbulent flow states that, the frictional resistance is proportional to the square of the velocity, the frictional resistance is independent of the pressure, the frictional resistance is proportional to the density of fluid and the frictional resistance slightly varies with temperature


2)   The velocity at which the fluid flow changes from viscous flow to a turbulent flow is called as ___________(Marks: 02)
- Published on 19 Oct 15

a. laminar velocity of fluid flow
b. turbulent velocity of fluid flow
c. critical velocity of fluid flow
d. none of the above
Answer  Explanation 

ANSWER: critical velocity of fluid flow

Explanation:
A liquid have steady viscous flow at only low velocity. The flow becomes turbulent after reaching certain velocity. This velocity is called as critical velocity of fluid flow.


3)   Which of the following is actually an ideal fluid?(Marks: 02)
- Published on 19 Oct 15

a. air
b. water
c. oil
d. none of the above
Answer  Explanation 

ANSWER: none of the above

Explanation:
The fluid which is incompressible and which has no viscosity is known as an ideal fluid. Water and oil have some viscosity among the above fluids. Viscosity of air can be negligible but it is not incompressible. Therefore ideal fluid is only a hypothetical fluid. All the existing fluids have some viscosity.


4)   The ratio of weight of fluid to the volume of the fluid is called as _________(Marks: 01)
- Published on 19 Oct 15

a. partial weight
b. partial volume
c. specific weight
d. specific volume
Answer  Explanation 

ANSWER: specific weight

Explanation:
Specific weight is defined as the weight of the fluid per unit volume.


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