Fluid Mechanics Sheet 1

1) Question.

The pressure intensity is same in all directions at a point -
Answer.
- 1
  
  only when fluid is frictionless and incompressible
- 2
  
  only when fluid is frictionless and is at rest
- 3
  
  only when fluid is frictionless
- 4
  
  when there is no relative motion of one fluid layer relative to other
Answer: 4

Explanation:
2) Question.

If a liquid has greater cohesion than adhesion with the solid, then the liquid in the capillary tube will -
Answer.
- 1
  
  rise with concave surface upward
- 2
  
  rise with convex surface upward
- 3
  
  depress with concave surface upward
- 4
  
  depress with convex surface upward
Answer: 4

Explanation:
3) Question.

Surface tension of water -
Answer.
- 1
  
  increases with decrease in temperature
- 2
  
  decreases with decrease in temperature
- 3
  
  is independent of temperature
- 4
  
  none of the above
Answer: 1

Explanation:
4) Question.

The intensity of pressure developed by surface tension of 0.075 N/m in a droplet of water of 0.075 mm diameter is -
Answer.
- 1
  
  $0.8 N / c m^{2}$
- 2
  
  $0.6 N / c m^{2}$
- 3
  
  $0.4 N / c m^{2}$
- 4
  
  $400 N / c m^{2}$
Answer: 3

Explanation:
5) Question.

Newton's law of viscosity relates -
Answer.
- 1
  
  intensity of pressure and rate of angular deformation
- 2
  
  shear stress and rate of angular deformation
- 3
  
  shear stress, viscosity and temperature
- 4
  
  viscosity and rate of angular deformation
Answer: 2

Explanation:
6) Question.

The viscosity of a gas -
Answer.
- 1
  
  decreases with increase in temperature.
- 2
  
  increases with increase in temperature.
- 3
  
  is independent of temperature.
- 4
  
  is independent of pressure for very high pressure intensities
Answer: 2

Explanation:
7) Question.

If the dynamic viscosity of a fluid is 0.5 poise and specific gravity is 0.5, then the kinematic viscosity of that fluid in stokes is -
Answer.
- 1
  
  0.25
- 2
  
  0.50
- 3
  
  1.0
- 4
  
  none of the above
Answer: 3

Explanation:
8) Question.

The unit of kinematic viscosity is -
Answer.
- 1
  
  $g m / c m - s e c^{2}$
- 2
  
  $d y n e - s e c / c m^{2}$
- 3
  
  $g m / c m^{2} - s e c$
- 4
  
  $c m^{2} / s e c$
Answer: 4

Explanation:
9) Question.

An ideal fluid is -
Answer.
- 1
  
  one which obeys Newton's law of viscosity
- 2
  
  frictionless and incompressible
- 3
  
  very viscous
- 4
  
  frictionless and compressible
Answer: 2

Explanation:
10) Question.

Pascal-second is the unit of -
Answer.
- 1
  
  pressure
- 2
  
  kinematic viscosity
- 3
  
  dynamic viscosity
- 4
  
  surface tension
Answer: 3

Explanation:
11) Question.

The coefficient of velocity for an orifice is given by (using usual notations) -
Answer.
- 1
  
  $\frac{x}{2 \sqrt{Y H}}$
- 2
  
  $\frac{2 x}{\sqrt{Y H}}$
- 3
  
  $\frac{x}{\sqrt{Y H}}$
- 4
  
  $\sqrt{\frac{x^{2}}{2 Y H}}$
Answer: 1

Explanation:
12) Question.

Which one of the following statements regarding reciprocating pump is correct ?
Answer.
- 1
  
  Friction head is mainly responsible for causing cavitation in a reciprocating pump at the beginning of the suction stroke.
- 2
  
  Effect of acceleration pressure on reciprocating pumps appears parabolic and has the maximum effect at the middle of the delivery stroke.
- 3
  
  Air vessel reduces the acceleration head and consequently reduces the effect of friction head also.
- 4
  
  The maximum permissible suction lift in a double acting reciprocating pump is independent of vapour pressure.
Answer: 3

Explanation:
13) Question.

Laminar flow occurs between extensive stationary plates. the kinetic energy correction factor is nearly
Answer.
- 1
  
  1.0
- 2
  
  1.5
- 3
  
  2.0
- 4
  
  2.3
Answer: 3

Explanation:
14) Question.

Shear velocity is
Answer.
- 1
  
  a non-dimensional quantity
- 2
  
  a fictitious quantity
- 3
  
  velocity of fluid at the edge of laminar sublayer
- 4
  
  the velocity of fluid at the edge of roughness element
Answer: 2

Explanation:
15) Question.

An error of 0.5% in the measurement of head in a V-notch causes an error of
Answer.
- 1
  
  0.5% in the discharge
- 2
  
  1.0% in the discharge
- 3
  
  1.25% in the discharge
- 4
  
  1.5% in the discharge
Answer: 3

Explanation:
16) Question.

In a fluid flow, the time of constant piezometric head passes through two points which have the same
Answer.
- 1
  
  elevation
- 2
  
  pressure
- 3
  
  velocity
- 4
  
  velocity potential
Answer: 4

Explanation:
17) Question.

The flow of water in a wash hand basin when it is being emptied through a central opening, is an example of
Answer.
- 1
  
  free vortex
- 2
  
  forced vortex
- 3
  
  rotational vortex
- 4
  
  Rankine vortex
Answer: 1

Explanation:
18) Question.

As the depth of immersion of a vertical plane surface increases, the location of pressure
Answer.
- 1
  
  comes closer to the centre of gravity of the area
- 2
  
  moves apart from the centre of gravity of the area
- 3
  
  ultimately coincides with the centre of gravity of the area
- 4
  
  remains unaffected
Answer: 1

Explanation:
19) Question.

The relationship $\frac{d p}{d x} = \frac{d τ}{d y}$ is valid for
Answer.
- 1
  
  irrotational flow
- 2
  
  non-uniform flow
- 3
  
  uniform flow
- 4
  
  unsteady flow
Answer: 3

Explanation:
20) Question.

In a Sutro weir, the rate of flow for all flows above the rectangular base of width W and depth 'a' is proportional to the head
Answer.
- 1
  
  above the crest
- 2
  
  above the rectangular box
- 3
  
  above a datum a/3 above the crest
- 4
  
  2a/3 above the crest
Answer: 3

Explanation:

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