Fluid Mechanics GATE Objective Questions

Fluid Mechanics : Objective Questions

1. Laminar developed flow at an average velocity of 5 m/s occurs in a pipe of 10 cm radius. The velocity at 5 cm radius is ?

A. 6.5 m/s

B. 7 m/s

C. 7.5 m/s

D. 8m/s

View Answer/Explanation

Correct Answer is C

Using the Formula

U = 2Uavg. [1 – (r/R)² ]

2. Flow separation is caused by –

A. a negative pressure gradient

B. a positive pressure gradient

C. reduction of pressure to local vapor pressure

D. thinning of boundary layer thickness to zero

View Answer/Explanation

Correct Answer is B

3. A centrifugal pump is started with its delivery valve kept –

A. fully closed

B. fully open

C. partially open

D. 50% open

View Answer/Explanation

Correct Answer is A

4. Ir-rotational flow occurs when?

A. there is no net rotation of the fluid element about its mass center

B. streamlines are curved

C. fluid element does not undergo any change in size or shape

D. flow takes place in a duct of uniform cross section at constant mass flow rate

View Answer/Explanation

Correct Answer is A

5. Which of the following forces act on a fluid at rest?

  1. Gravity force
  2. Hydrostatic force
  3. Surface tension
  4. Viscous force

A. All of these

B. 1 and 2

C. 1, 2 and 4

D. 1, 2 and 3

View Answer/Explanation

Correct Answer is D

Viscous force do not act when fluid is at rest.

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