50 Civil Engineering Fluid Mechanics MCQ with Answers PDF

Prepare with these fluid mechanics mcq for various exams and interview

Fluid mechanics mcq

1. A rectangular block 2 m long, 1 m wide and 1 m deep floats in water, the depth of immersion being 0.5 m. If water weighs 10 kN/m3, then the weight of the block is
a) 5 kN
b) 10 kN
c) 15 kN
d) 20 kN

Answer: b) 10kN

2. The point in the immersed body through which the resultant pressure of the liquid may be taken to act is known as
a) center of gravity
b) center of buoyancy
c) center of pressure
d) metacentre

Answer: c) center of pressure

3. If a vessel containing liquid moves downward with a constant acceleration equal to ‘g’ then
a) the pressure throughout the liquid mass is atmospheric
b) there will be vacuum in the liquid
c) the pressure in the liquid mass is greater than hydrostatic pressure
d) none of the above

Answer: a) the pressure throughout the liquid mass is atmospheric

4. When a liquid rotates at a constant angular velocity about a vertical axis as a rigid body, the pressure intensity varies
a) linearly with radial distance
b) as the square of the radial distance
c) inversely as the square of the radial distance
d) inversely as the radial distance

Answer: b) as the square of the radial distance

5.The eddy viscosity for turbulent flow is
a) a function of temperature only
b) a physical property of the fluid.
c) dependent on the flow
d) independent of the flow

Answer: c) dependent on the flow

6. Flow at constant rate through a tapering pipe is
i) steady flow
ii) uniform flow
iii) unsteady flow
iv) non-uniform flow

The correct answer is
a) (i) and (ii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)

Answer: b) (i)and(iv)

7. When the velocity distribution is uniform over the cross-section, the correction factor for momentum is
a) 0
b) 1
c) 4/3
d) 2

Answer: b) 1

8. Least possible value of correction factor for
i) kinetic energy is zero
ii) kinetic energy is 1
iii) momentum is zero
iv) momentum is 1

The correct statements are
a) (i) and (iii)
b) (ii) and (iii)
c) (i) and (iv)
d) (ii) and (iv)

Answer: d) (ii) and (iv)

9. The viscosity of a gas
a) decreases with increase in temperature
b) increases with increase in temperature
c) is independent of temperature
d) is independent of pressure for very high pressure intensities

Answer: b) increases with increase in temperature

10. The unit of kinematic viscosity is
a) gm/cm-sec2
b) dyne-sec/cm2
c) gm/cm2-sec
d) cm2/sec

Answer: d) cm2/sec

11. 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
a) 0.25
b) 0.50
c) 1.0
d) none of the above

Answer: c) 1.0

12. Pascal-second is the unit of
a) pressure
b) kinematic viscosity
c) dynamic viscosity
d) surface tension

Answer: c) dynamic viscosity

13. Centre of buoyancy always
a) coincides with the centre of gravity
b) coincides with the centroid of the volume of fluid displaced
c) remains above the centre of gravity
d) remains below the centre of gravity

Answer: b) coincides with the centroid of the volume of fluid displaced

14. The discharge through a V- notch varies as
a) H1/2
b) H3’2
c) H5/2
d) H5’4 where H is head.

Answer: c) H5/2

15. Coefficient of velocity of venturimeter
a) is independent of Reynolds number
b) decreases with higher Reynolds number
c) is equal to the coefficient of discharge of venturimeter
d) none of the above

Answer: c) is equal to the coefficient of discharge of venturimeter


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16. Ay between two stream lines represents
a) velocity
b) discharge
c) head
d) pressure

Answer: b) discharge

17. The pressure at the summit of a syphon is
a) equal to atmospheric
b) less than atmospheric
c) more than atmospheric
d) none of the above

Answer: b) less than atmospheric

18. Coefficient of velocity for Borda’s mouthpiece running full is
a) 0.611
b) 0.707
c) 0.855
d) 1.00

Answer: b) 0.707

19. The major loss of energy in long pipes is due to
a) sudden enlargement
b) sudden contraction
c) gradual contraction or enlargement
d) friction

Answer: d) friction

20. Coefficient of contraction for an external cylindrical mouthpiece is
a) 1.00
b) 0.855
c) 0.7H
d) 0.611

Answer: a) 1.00

21. In a Sutro weir, the discharge is proportional to
a) H1/2
b) H3/2
c) H5/2
d) H
where H is head.

Answer: d) H

22. The boundary layer thickness in turbulent flow varies as
a) x”7
b) x,/2
c) x4/5
d) x3/5
where x is the distance from leading edge.

Answer: b) x,/2

23. In case of an airfoil, the separation of flow occurs
a) at the extreme rear of body
b) at the extreme front of body
c) midway between rear and front of body
d) any where between rear and front of body depending upon Reynolds number

Answer: a) at the extreme rear of body

24. In which of the following the friction drag is generally larger than pressure drag?
a) a circular disc or plate held normal to flow
b) a sphere
c) a cylinder
d) an airfoil

Answer: d) an airfoil

25. Separation of flow occurs when
a) the pressure intensity reaches a minimum
b) the cross-section of a channel is reduced
c) the boundary layer comes to rest
d) all of the above

Answer: c) the boundary layer comes to rest


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