Fluid Mechanics: Objective Questions

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Read More- Heat and Mass Transfer: Objective Questions with Answers

1. Laminar developed flow at an average velocity of 5 m/s occurs in a pipe of a 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

Click for 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 the local vapor pressure

D. thinning of boundary layer thickness to zero

Click for 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

Click for 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 a uniform cross-section at a constant mass flow rate

Click for 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

Click for Answer/Explanation

Correct Answer is D

Viscous force does not act when fluid is at rest.

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