XAT - Fluid Mechanics 1000+ MCQ [Solved] PDF Download

1. Manometer is used to measure
A. Pressure in pipes, channels etc.
B. Atmospheric pressure
C. Very low pressure
D. Difference of pressure between two points
Answer : A

2. The height of a water column equivalent to a pressure of 0.15 MPa is
A. 15.3 m
B. 25.3 m
C. 35.3 m
D. 45.3 m
Answer : A

3. The line of action of the buoyant force acts through the
A. Centroid of the volume of fluid vertically above the body
B. Centre of the volume of floating body
C. Center of gravity of any submerged body
D. Centroid of the displaced volume of fluid
Answer : D

4. The viscosity of a liquid __________ its rate of flow through a hole in a vessel.
A. Effects
B. Does not effect
C. Both A and B
D. None of these
Answer : A

5. A fluid having no viscosity is known as
A. Real fluid
B. Ideal fluid
C. Newtonian fluid
D. Non-Newtonian fluid
Answer : B

6. The discharge through a convergent mouthpiece is __________ the discharge through an internal mouthpiece of the same diameter and head of water.
A. Equal to
B. One-half
C. Three fourth
D. Double
Answer : D

7. Buoyant force is
A. The resultant force acting on a floating body
B. The resultant force on a body due to the fluid surrounding it
C. Equal to the volume of liquid displaced
D. The force necessary to maintain equilibrium of a submerged body
Answer : B

8. Barometer is used to measure
A. Velocity of liquid
B. Atmospheric pressure
C. Pressure in pipes and channels
D. Difference of pressure between two points in a pipe
Answer : B

9. Liquids
A. Cannot be compressed
B. Occupy definite volume
C. Are not affected by change in pressure and temperature
D. None of the above
Answer : D

10. The depth of the centre of pressure on a vertical rectangular gate 8 m wide and 6 m high, when the water surface coincides with the top of the gate, is
A. 2.4 m
B. 3.0 m
C. 4.0 m
D. 5.0 m
Answer : B

11. The volume of a fluid __________ as the pressure increases.
A. Remains same
B. Decreases
C. Increases
D. None of these
Answer : B

12. The value of bulk modulus of a fluid is required to determine
A. Reynold's number
B. Froude's number
C. Mach number
D. Euler's number
Answer : C

13. The liquid used in manometers should have
A. Low density
B. High density
C. Low surface tension
D. High surface tension
Answer : D

14. The density of water is 1000 kg/m3 at
A. 0° C
B. 0° K
C. 4° C
D. 20° C
Answer : C

15. Metacentric height is given as the distance between
A. The center of gravity of the body and the metacentre
B. The center of gravity of the body and the center of buoyancy
C. The center of gravity of the body and the center of pressure
D. Center of buoyancy and metacentre
Answer : A

16. According to Bernoulli's equation for steady ideal fluid flow
A. Principle of conservation of mass holds
B. Velocity and pressure are inversely proportional
C. Total energy is constant throughout
D. The energy is constant along a streamline but may vary across streamlines
Answer : D

17. The body will float if the force of buoyancy is __________ the weight of the liquid displaced.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : C

18. The critical depth for a channel is given by (where q = Unit discharge (discharge per unit width) through the channel)
A. (q/g)^1/2
B. (q²/g)^1/3
C. (q³/g)^1/4
D. (q?/g)^1/5
Answer : B

19. The discharge through a channel of trapezoidal section is maximum when
A. Width of channel at the top is equal to twice the width at the bottom
B. Depth of channel is equal to the width at the bottom
C. The sloping side is equal to half the width at the top
D. The sloping side is equal to the width at the bottom
Answer : C

20. The discharge through a channel of rectangular section will be maximum, if
A. Its depth is twice the breadth
B. Its breadth is twice the depth
C. Its depth is thrice the breadth
D. Its breadth is thrice the depth
Answer : B

21. The coefficient of discharge in case of internal mouthpiece is __________ that of external mouthpiece.
A. Less than
B. More than
C. Equal to
D. None of these
Answer : A

22. To avoid vaporisation in the pipe line, the pipe line over the ridge is laid such that it is not more than
A. 2.4 m above the hydraulic gradient
B. 6.4 m above the hydraulic gradient
C. 10.0 m above the hydraulic gradient
D. 5.0 above the hydraulic gradient
Answer : B

23. The hydraulic mean depth for a circular pipe of diameter (d) is
A. d/6
B. d/4
C. d/2
D. d
Answer : B

24. The meatcentric height is the distance between the
A. Centre of gravity of the floating body and the centre of buoyancy
B. Centre of gravity of the floating body and the metacentre
C. Metacentre and centre of buoyancy
D. Original centre of buoyancy and new centre of buoyancy
Answer : B

25. Kinematic viscosity is equal to
A. Dynamic viscosity/density
B. Dynamic viscosity × density
C. Density/dynamic viscosity
D. 1/dynamic viscosity × density
Answer : A

26. Ratio of inertia force to elastic force is known as
A. Mach number
B. Froude number
C. Reynolds number
D. Weber's number
Answer : A

27. When a body floating in a liquid, is displaced slightly, it oscillates about
A. C.G. of body
B. Center of pressure
C. Center of buoyancy
D. Metacentre
Answer : D

28. The value of the coefficient of compressibility for water at ordinary pressure and temperature in kg/cm is equal to
A. 2100
B. 2700
C. 10,000
D. 21,000
Answer : D

29. A Piezometer tube is used only for measuring
A. Low pressure
B. High pressure
C. Moderate pressure
D. Vacuum pressure
Answer : C

30. The rise of liquid along the walls of a revolving cylinder about the initial level is __________ the depression of the liquid at the axis of rotation.
A. Same as
B. Less than
C. More than
D. None of these
Answer : A

31. An internal mouthpiece is said to be running free if the length of the mouthpiece is __________ the diameter of the orifice.
A. Less than twice
B. More than twice
C. Less than three times
D. More than three times
Answer : C

32. The loss of pressure head in case of laminar flow is proportional to
A. Velocity
B. (Velocity)²
C. (Velocity)³
D. (Velocity)⁴
Answer : A

33. One poise is equal to
A. 0.1 N-s/m²
B. 1 N-s/m²
C. 10 N-s/m²
D. 100 N-s/m²
Answer : A

34. The discharge over a rectangular notch is
A. Inversely proportional to H^3/2
B. Directly proportional to H^3/2
C. Inversely proportional to H^5/2
D. Directly proportional to H^5/2
Answer : B

35. Which of the following instrument can be used for measuring speed of a submarine moving in deep sea?
A. Venturimeter
B. Orifice plate
C. Hot wire anemometer
D. Pitot tube
Answer : D

36. The property of a liquid which offers resistance to the movement of one layer of liquid over another adjacent layer of liquid, is called
A. Surface tension
B. Compressibility
C. Capillarity
D. Viscosity
Answer : D

37. Working principle of dead weight pressure gauge tester is based on
A. Pascal's law
B. Dalton's law of partial pressure
C. Newton's law of viscosity
D. Avogadro's hypothesis
Answer : A

38. The pressure of the liquid flowing through the divergent portion of a Venturimeter
A. Remains constant
B. Increases
C. Decreases
D. Depends upon mass of liquid
Answer : C

39. The force exerted by a moving fluid on an immersed body is directly proportional to the rate of change of momentum due to the presence of the body. This statement is called
A. Newton's law of motion
B. Newton's law of cooling
C. Newton's law of viscosity
D. Newton's law of resistance
Answer : D

40. The total head of a liquid particle in motion is equal to
A. Pressure head + kinetic head + potential head
B. Pressure head - (kinetic head + potential head)
C. Potential head - (pressure head + kinetic head)
D. Kinetic head - (pressure head + potential head)
Answer : A

41. A water tank contains 1.3 m deep water. The pressure exerted by the water per metre length of the tank is
A. 2.89 kN
B. 8.29 kN
C. 9.28 kN
D. 28.9 kN
Answer : B

42. According to Chezy's formula, the discharge through an open channel is (where A = Area of flow, C = Chezy's constant, m = Hydraulic mean depth, and i = Uniform slope in bed)
A. A × ?(m × i)
B. C × ?(m × i)
C. AC × ?(m × i)
D. mi × ?(A × C)
Answer : C

43. Fluid is a substance that
A. Cannot be subjected to shear forces
B. Always expands until it fills any container
C. Has the same shear stress at a point regardless of its motion
D. Cannot remain at rest under action of any shear force
Answer : D

44. The hammer blow in pipes occurs when
A. There is excessive leakage in the pipe
B. The pipe bursts under high pressure of fluid
C. The flow of fluid through the pipe is suddenly brought to rest by closing of the valve
D. The flow of fluid through the pipe is gradually brought to rest by closing of the valve
Answer : C

45. Select the correct statement
A. Weber's number is the ratio of inertia force to elastic force.
B. Weber's number is the ratio of gravity force to surface tension force.
C. Weber's number is the ratio of viscous force to pressure force.
D. Weber's number is the ratio of inertia force to surface tension force.
Answer : D

46. An error of 1% in measuring head over the crest of the notch (H) will produce an error of __________ in discharge over a triangular notch,
A. 1 %
B. 1.5 %
C. 2 %
D. 2.5 %
Answer : D

47. The efficiency of power transmission through pipe is (where H = Total supply head, and hf = Head lost due to friction in the pipe)
A. (H - hf )/H
B. H/(H - hf )
C. (H + hf )/H
D. H/(H + hf )
Answer : A

48. The flow of water through the hole in the bottom of a wash basin is an example of
A. Steady flow
B. Uniform flow
C. Free vortex
D. Forced vortex
Answer : C

49. The force per unit length is the unit of
A. Surface tension
B. Compressibility
C. Capillarity
D. Viscosity
Answer : A

50. The flow in a pipe is neither laminar nor turbulent when Reynold number is
A. Less than 2000
B. Between 2000 and 2800
C. More than 2800
D. None of these
Answer : B