CLAT PG - Fluid Mechanics 1000+ MCQ [Solved] PDF Download

1. According to Darcy's formula, the loss of head due to friction in the pipe is (where f = Darcy's coefficient, l = Length of pipe, v = Velocity of liquid in pipe, and d = Diameter of pipe)
A. flv²/2gd
B. flv²/gd
C. 3flv²/2gd
D. 4flv²/2gd
Answer : D

2. The divergent portion of a Venturimeter is made longer than convergent portion in order to
A. Avoid the tendency of breaking away the stream of liquid
B. To minimise frictional losses
C. Both (A) and (B)
D. None of these
Answer : C

3. An ideal flow of any fluid must fulfil the following
A. Newton's law of motion
B. Newton's law of viscosity
C. Pascal' law
D. Continuity equation
Answer : D

4. The normal stress is same in all directions at a point in a fluid
A. Only when the fluid is frictionless
B. Only when the fluid is incompressible and has zero viscosity
C. When there is no motion of one fluid layer relative to an adjacent layer
D. Irrespective of the motion of one fluid layer relative to an adjacent layer
Answer : C

5. In a venturi-flume, the flow takes place at
A. Atmospheric pressure
B. Gauge pressure
C. Absolute pressure
D. None of these
Answer : A

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

7. The imaginary line drawn in the fluid in such a way that the tangent to any point gives the direction of motion at that point, is known as
A. Path line
B. Stream line
C. Steak line
D. Potential line
Answer : B

8. Mercury does not wet glass. This is due to property of liquid known as
A. Adhesion
B. Cohesion
C. Surface tension
D. Viscosity
Answer : C

9. A large Reynold number is indication of
A. Smooth and streamline flow
B. Laminar flow
C. Steady flow
D. Highly turbulent flow
Answer : D

10. Metacentre is the point of intersection of
A. Vertical upward force through e.g. of body and center line of body
B. Buoyant force and the center line of body
C. Midpoint between e.g. and center of buoyancy
D. All of the above
Answer : B

11. When a cylindrical vessel containing liquid is revolved about its vertical axis at a constant angular velocity, the pressure
A. Varies as the square of the radial distance
B. Increases linearly as its radial distance
C. Increases as the square of the radial distance
D. Decreases as the square of the radial distance
Answer : A

12. Cavitation will begin when
A. The pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid
B. Pressure becomes more than critical pressure
C. Flow is increased
D. Pressure is increased
Answer : A

13. The center of gravity of the volume of the liquid displaced by an immersed body is called
A. Metacentre
B. Center of pressure
C. Center of buoyancy
D. Center of gravity
Answer : C

14. The intensity of pressure at any point, in a liquid, is __________ to the depth of liquid from the surface.
A. Equal
B. Directly proportional
C. Inversely proportional
D. None of these
Answer : B

15. Free surface of a liquid tends to contract to the smallest possible area due to force of
A. Surface tension
B. Viscosity
C. Friction
D. Cohesion
Answer : A

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

17. Choose the correct relationship
A. Specific gravity = gravity × density
B. Dynamic viscosity = kinematic viscosity × density
C. Gravity = specific gravity × density
D. Kinematic viscosity = dynamic viscosity × density
Answer : B

18. The equation of continuity holds good when the flow
A. Is steady
B. Is one dimensional
C. Velocity is uniform at all the cross sections
D. All of the above
Answer : D

19. Practical fluids
A. Are viscous
B. Possess surface tension
C. Are compressible
D. Possess all the above properties
Answer : D

20. 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

21. 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

22. 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

23. The dynamic viscosity of gases __________ with rise in temperature.
A. Remain unaffected
B. Increases
C. Decreases
D. None of these
Answer : B

24. Falling drops of water become spheres due to the property of
A. Adhesion
B. Cohesion
C. Surface tension
D. Viscosity
Answer : C

25. An internal mouthpiece is said to be running __________ if the length of the mouthpiece is more than three times the diameter of the orifice.
A. Free
B. Partially
C. Full
D. None of these
Answer : C

26. A flow in which the quantity of liquid flowing per second is constant, is called __________ flow.
A. Steady
B. Streamline
C. Turbulent
D. Unsteady
Answer : A

27. In an internal mouthpiece, if the jet after contraction does not touch the sides of the mouthpiece, then the mouthpiece is said to be
A. Running full
B. Running free
C. Partially running full
D. Partially running free
Answer : B

28. The discharge through a channel of circular section will be maximum when the depth of water is __________ the diameter of the circular channel.
A. 0.34 times
B. 0.67 times
C. 0.81 times
D. 0.95 times
Answer : D

29. The property by virtue of which a liquid opposes relative motion between its different layers is called
A. Surface tension
B. Coefficient of viscosity
C. Viscosity
D. Osmosis
Answer : C

30. The error in discharge (dQ/Q) to the error in measurement of head (dH/H) over a rectangular notch is given by
A. dQ/Q = (1/2) × (dH/H)
B. dQ/Q = (3/4) × (dH/H)
C. dQ/Q = (dH/H)
D. dQ/Q = (3/2) × (dH/H)
Answer : D

31. Center of pressure on an inclined plane is
A. At the Centroid
B. Above the Centroid
C. Below the Centroid
D. At metacentre
Answer : C

32. A vessel of 4 m³ contains oil which weighs 30 kN. The specific weight of the oil is
A. 4.5 kN/m³
B. 6 kN/m³
C. 7.5 kN/m³
D. 10 kN/m³
Answer : C

33. For pipes, turbulent flow occurs when Reynolds number is
A. Less than 2000
B. Between 2000 and 4000
C. More than 4000
D. Less than 4000
Answer : C

34. Rotameter is a device used to measure
A. Absolute pressure
B. Velocity of fluid
C. Flow
D. Rotation
Answer : C

35. For a body floating in a liquid the normal pressure exerted by the liquid acts at
A. Bottom surface of the body
B. C.G. of the body
C. Metacentre
D. All points on the surface of the body
Answer : D

36. The flow in a pipe or channel is said to be non-uniform when
A. The liquid particles at all sections have the same velocities
B. The liquid particles at different sections have different velocities
C. The quantity of liquid flowing per second is constant
D. Each liquid particle has a definite path
Answer : B

37. The velocity at which the laminar flow stops, is known as
A. Velocity of approach
B. Lower critical velocity
C. Higher critical velocity
D. None of these
Answer : B

38. 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

39. Capillary action is due to the
A. Surface tension
B. Cohesion of the liquid
C. Adhesion of the liquid molecules and the molecules on the surface of a solid
D. All of the above
Answer : D

40. When the Mach number is less than unity, the flow is called
A. Sub-sonic flow
B. Sonic flow
C. Super-sonic flow
D. Hyper-sonic flow
Answer : A

41. A piece of wood having weight 5 kg floats in water with 60% of its volume under the liquid. The specific gravity of wood is
A. 0.83
B. 0.6
C. 0.4
D. 0.3
Answer : B

42. A thick liquid like syrup has a __________ viscosity than a light liquid like water.
A. Lesser
B. Greater
C. Same
D. None of these
Answer : B

43. The discharge through a wholly drowned orifice is given by (where H1 = Height of water (on the upstream side) above the top of the orifice, H2 = Height of water (on the downstream side) above the bottom of the orifice, and H = Difference between two water levels on either side of the orifice)
A. Q = C_d × bH? × ?(2gh)
B. Q = C_d × bH₂ × ?(2gh)
C. Q = C_d × b (H₂ - H₁) × ?(2gh)
D. Q = C_d × bH × ?(2gh)
Answer : C

44. Which of the following manometer has highest sensitivity?
A. U-tube with water
B. Inclined U-tube
C. U-tube with mercury
D. Micro-manometer with water
Answer : D

45. 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

46. 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

47. The factional resistance of a pipe varies approximately with __________ of the liquid.
A. Pressure
B. Velocity
C. Square of velocity
D. Cube of velocity
Answer : C

48. Liquids transmit pressure equally in all the directions. This is according to
A. Boyle's law
B. Archimedes principle
C. Pascal's law
D. Newton's formula
Answer : C

49. An object having 10 kg mass weighs 9.81 kg on a spring balance. The value of 'g' at this place is
A. 10 m/sec²
B. 9.81 m/sec²
C. 9.75 m/sec²
D. 9 m/sec
Answer : A

50. 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