SSC CPO - Fluid Mechanics 1000+ MCQ [Solved] PDF Download

1. 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

2. The most economical section of a trapezoidal channel is one which has hydraulic mean depth equal to
A. 1/2 × depth
B. 1/2 × breadth
C. 1/2 × sloping side
D. 1/4 × (depth + breadth)
Answer : A

3. In order to increase sensitivity of U-tube manometer, one leg is usually inclined by angle ?. Sensitivity of inclined tube to sensitivity of Utube is equal to
A. Sin?
B. 1/Sin?
C. Cos?
D. 1/Cos?
Answer : B

4. Choose the wrong statement
A. The center of buoyancy is located at the center of gravity of the displaced liquid
B. For stability of a submerged body, the center of gravity of body must lie directly below the center of buoyancy
C. If C.G. and center of buoyancy coincide, the submerged body must lie at neutral equilibrium for all positions
D. All floating bodies are stable
Answer : D

5. When a cylindrical vessel containing liquid is resolved, the surface of the liquid takes the shape of
A. A triangle
B. A paraboloid
C. An ellipse
D. None of these
Answer : B

6. The flow in a pipe or channel is said to be 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 : A

7. Water is __________ liquid.
A. A compressible
B. An incompressible
C. Both A and B
D. None of these
Answer : B

8. The length AB of a pipe ABC in which the liquid is flowing has diameter (d₁) and is suddenly contracted to diameter (d₂) at B which is constant for the length BC. The loss of head due to sudden contraction, assuming coefficient of contraction as 0.62, is
A. v?²/2g
B. v?²/2g
C. 0.5 v?²/2g
D. 0.375 v?²/2g
Answer : D

9. The continuity equation is connected with
A. Open channel/pipe flow
B. Compressibility of fluids
C. Conservation of mass
D. Steady/unsteady flow
Answer : C

10. The error in discharge (dQ/Q) to the error in measurement of head (dH/H) over a triangular notch is given by
A. dQ/Q = 3/2 × (dH/H)
B. dQ/Q = 2 × (dH/H)
C. dQ/Q = 5/2 × (dH/H)
D. dQ/Q = 3 × (dH/H)
Answer : C

11. The total pressure force on a plane area is equal to the area multiplied by the intensity of pressure at the Centroid, if
A. The area is horizontal
B. The area is vertical
C. The area is inclined
D. All of the above
Answer : D

12. The weight per unit volume of a liquid at a standard temperature and pressure is called
A. Specific weight
B. Mass density
C. Specific gravity
D. None of these
Answer : A

13. 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

14. 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

15. Two pipe systems can be said to be equivalent, when the following quantities are same
A. Friction loss and flow
B. Length and diameter
C. Flow and length
D. Friction factor and diameter
Answer : A

16. A manometer is used to measure
A. Low pressure
B. Moderate pressure
C. High pressure
D. Atmospheric pressure
Answer : C

17. A flow is called sub-sonic, if the Mach number is
A. Less than unity
B. Unity
C. Between 1 and 6
D. More than 6
Answer : A

18. The region between the separation streamline and the boundary surface of the solid body is known as
A. Wake
B. Drag
C. Lift
D. Boundary layer
Answer : A

19. When a plate is immersed in a liquid parallel to the flow, it will be subjected to a pressure __________ that if the same plate is immersed perpendicular to the flow.
A. Less than
B. More than
C. Equal to
D. None of these
Answer : A

20. If the depth of water in an open channel is greater than the critical depth, the flow is called
A. Critical flow
B. Turbulent flow
C. Tranquil flow
D. Torrential flow
Answer : C

21. 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

22. One stoke is equal to
A. 10^-2 m²/s
B. 10^-3 m²/s
C. 10^-4 m²/s
D. 10^-6 m²/s
Answer : C

23. 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

24. When the pressure intensity at a point is more than the local atmospheric pressure, then the difference of these two pressures is called
A. Gauge pressure
B. Absolute pressure
C. Positive gauge pressure
D. Vacuum pressure
Answer : C

25. For very great pressures, viscosity of moss gases and liquids
A. Remain same
B. Increases
C. Decreases
D. Shows erratic behaviour
Answer : D

26. The coefficient of discharge for an external mouthpiece depends upon
A. Velocity of liquid
B. Pressure of liquid
C. Area of mouthpiece
D. Length of mouthpiece
Answer : D

27. The Francis formula for the discharge over Cipoletti weir is
A. 1.84 LH^1/2
B. 1.84 LH
C. 1.84 LH^3/2
D. 1.84 LH^5/2
Answer : C

28. Bulk modulus of a fluid __________ as the pressure increases.
A. Remain same
B. Decreases
C. Increases
D. None of these
Answer : C

29. 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

30. Which of the following is an example of laminar flow?
A. Underground flow
B. Flow past tiny bodies
C. Flow of oil in measuring instruments
D. All of these
Answer : D

31. The loss of head due to friction in a pipe of uniform diameter in which a viscous flow is taking place, is (where RN = Reynold number)
A. 1/R_N
B. 4/R_N
C. 16/R_N
D. 64/R_N
Answer : C

32. A flow is called super-sonic if the
A. Velocity of flow is very high
B. Discharge is difficult to measure
C. Mach number is between 1 and 6
D. None of these
Answer : C

33. The fluid forces considered in the Navier Stokes equation are
A. Gravity, pressure and viscous
B. Gravity, pressure and turbulent
C. Pressure, viscous and turbulent
D. Gravity, viscous and turbulent
Answer : A

34. 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

35. The resultant upward pressure of a fluid on a floating body is equal to the weight of the fluid displaced by the body. This definition is according to
A. Buoyancy
B. Equilibrium of a floating body
C. Archimedes' principle
D. Bernoulli's theorem
Answer : C

36. Newton's law of viscosity is a relationship between
A. Shear stress and the rate of angular distortion
B. Shear stress and viscosity
C. Shear stress, velocity and viscosity
D. Pressure, velocity and viscosity
Answer : A

37. 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

38. The pressure intensity in kN/m2 (or kPa) at any point in a liquid is (where w = Specific weight of liquid, and h = Depth of liquid from the surface)
A. w
B. wh
C. w/h
D. h/w
Answer : B

39. The pressure in the air space above an oil (sp. gr. 0.8) surface in a tank is 0.1 kg/cm. The pressure at 2.5 m below the oil surface will be
A. 2 metres of water column
B. 3 metres of water column
C. 3.5 metres of water column
D. 4 m of water column
Answer : B

40. A pipe of length more than double the diameter of orifice fitted externally or internally to the orifice is called a
A. Notch
B. Weir
C. Mouthpiece
D. Nozzle
Answer : C

41. 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

42. At the center line of a pipe flowing under pressure where the velocity gradient is zero, the shear stress will be
A. Minimum
B. Maximum
C. Zero
D. Could be any value
Answer : D

43. For similarity, in addition to models being geometrically similar to prototype, the following in both cases should also be equal
A. Ratio of inertial force to force due to viscosity
B. Ratio of inertial force to force due to gravitation
C. Ratio of inertial force to force due to surface tension
D. All the four ratios of inertial force to force due to viscosity, gravitation, surface tension, and elasticity
Answer : D

44. 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

45. A piece of metal of specific gravity 13.6 is placed in mercury of specific gravity 13.6, what fraction of it volume is under mercury?
A. The metal piece will simply float over the mercury
B. The metal piece will be immersed in mercury by half
C. Whole of the metal piece will be immersed with its top surface just at mercury level
D. Metal piece will sink to the bottom
Answer : C

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

47. If mercury in a barometer is replaced by water, the height of 3.75 cm of mercury will be following cm of water
A. 51 cm
B. 50 cm
C. 52 cm
D. 52.2 cm
Answer : A

48. The volumetric change of the fluid caused by a resistance is known as
A. Volumetric strain
B. Volumetric index
C. Compressibility
D. Adhesion
Answer : C

49. The centre of gravity of the volume of the liquid displaced by an immersed body is called
A. Centre of gravity
B. Centre of pressure
C. Metacentre
D. Centre of buoyancy
Answer : D

50. 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