UPSC CSE - Fluid Mechanics 1000+ MCQ [Solved] PDF Download
Thursday 9th of March 2023
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1. The Metacentric heights of two floating bodies A and B are 1 m and 1.5 m respectively. Select the correct statement.
A. The bodies A and B have equal stability
B. The body A is more stable than body B
C. The body B is more stable than body A
D. The bodies A and B are unstable
Answer : C
A. The bodies A and B have equal stability
B. The body A is more stable than body B
C. The body B is more stable than body A
D. The bodies A and B are unstable
Answer : C
2. A flow whose streamline is represented by a straight line, is called __________ dimensional flow.
A. One
B. Two
C. Three
D. Four
Answer : A
A. One
B. Two
C. Three
D. Four
Answer : A
3. 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
A. At the Centroid
B. Above the Centroid
C. Below the Centroid
D. At metacentre
Answer : C
4. In case of flow through parallel pipes,
A. The head loss for all the pipes is same
B. The total discharge is equal to the sum of discharges in the various pipes
C. The total head loss is the sum of head losses in the various pipes
D. Both (A) and (B)
Answer : D
A. The head loss for all the pipes is same
B. The total discharge is equal to the sum of discharges in the various pipes
C. The total head loss is the sum of head losses in the various pipes
D. Both (A) and (B)
Answer : D
5. According to Newton's law of viscosity, the shear stress on a layer of a fluid is __________ to the rate of shear strain.
A. Equal to
B. Directly proportional
C. Inversely proportional
D. None of these
Answer : B
A. Equal to
B. Directly proportional
C. Inversely proportional
D. None of these
Answer : B
6. 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
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
7. A weir is said to be narrow-crested weir, if the width of the crest of the weir is __________ half the height of water above the weir crest.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B
8. The process of diffusion of one liquid into the other through a semi permeable membrane is called
A. Viscosity
B. Osmosis
C. Surface tension
D. Cohesion
Answer : B
A. Viscosity
B. Osmosis
C. Surface tension
D. Cohesion
Answer : B
9. 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
A. flv²/2gd
B. flv²/gd
C. 3flv²/2gd
D. 4flv²/2gd
Answer : D
10. 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
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
11. The total pressure on the surface of a vertical sluice gate 2 m x 1 m with its top 2 m surface being 0.5 m below the water level will be
A. 500 kg
B. 1000 kg
C. 1500 kg
D. 2000 kg
Answer : D
A. 500 kg
B. 1000 kg
C. 1500 kg
D. 2000 kg
Answer : D
12. A moving fluid mass may be brought to a static equilibrium position, by applying an imaginary inertia force of the same magnitude as that of the accelerating force but in the opposite direction. This statement is called
A. Pascal's law
B. Archimedess principle
C. D-Alembert's principle
D. None of these
Answer : C
A. Pascal's law
B. Archimedess principle
C. D-Alembert's principle
D. None of these
Answer : C
13. The pressure at a point in a fluid will not be same in all the directions when the fluid is
A. Moving
B. Viscous
C. Viscous and static
D. Viscous and moving
Answer : D
A. Moving
B. Viscous
C. Viscous and static
D. Viscous and moving
Answer : D
14. The flow which neglects changes in a transverse direction is known as
A. One dimensional flow
B. Uniform flow
C. Steady flow
D. Turbulent flow
Answer : A
A. One dimensional flow
B. Uniform flow
C. Steady flow
D. Turbulent flow
Answer : A
15. 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
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
16. A differential manometer is used to measure
A. Atmospheric pressure
B. Pressure in pipes and channels
C. Pressure in Venturimeter
D. Difference of pressures between two points in a pipe
Answer : D
A. Atmospheric pressure
B. Pressure in pipes and channels
C. Pressure in Venturimeter
D. Difference of pressures between two points in a pipe
Answer : D
17. The shear stress-strain graph for a Newtonian fluid is a
A. Straight line
B. Parabolic curve
C. Hyperbolic curve
D. Elliptical
Answer : A
A. Straight line
B. Parabolic curve
C. Hyperbolic curve
D. Elliptical
Answer : A
18. 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
A. 51 cm
B. 50 cm
C. 52 cm
D. 52.2 cm
Answer : A
19. 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
A. Steady flow
B. Uniform flow
C. Free vortex
D. Forced vortex
Answer : C
20. The total pressure on an immersed surface inclined at an angle ? with the liquid surface is
A. wA
B. wx
C. wAx
D. wAx/sin?
Answer : C
A. wA
B. wx
C. wAx
D. wAx/sin?
Answer : C
21. The specific weight of sea water is __________ that of pure water.
A. Same as
B. Less than
C. More than
D. None of these
Answer : C
A. Same as
B. Less than
C. More than
D. None of these
Answer : C
22. 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
A. Velocity of liquid
B. Pressure of liquid
C. Area of mouthpiece
D. Length of mouthpiece
Answer : D
23. One cubic metre of water weighs
A. 100 litres
B. 250 litres
C. 500 litres
D. 1000 litres
Answer : D
A. 100 litres
B. 250 litres
C. 500 litres
D. 1000 litres
Answer : D
24. 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
A. Adhesion
B. Cohesion
C. Surface tension
D. Viscosity
Answer : C
25. To avoid an interruption in the flow of a siphon, an air vessel is provided
A. At the inlet
B. At the outlet
C. At the summit
D. At any point between inlet and outlet
Answer : C
A. At the inlet
B. At the outlet
C. At the summit
D. At any point between inlet and outlet
Answer : C
26. An error of 1% in measuring head over the apex 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
A. 1 %
B. 1.5 %
C. 2 %
D. 2.5 %
Answer : D
27. If w is the specific weight of liquid and k the depth of any point from the surface, then pressure intensity at that point will be
A. h
B. wh
C. w/h
D. h/w
Answer : B
A. h
B. wh
C. w/h
D. h/w
Answer : B
28. A jet of water discharging from a 40 mm diameter orifice has a diameter of 32 mm at its vena contracta. The coefficient of contraction is
A. 0.46
B. 0.64
C. 0.78
D. 0.87
Answer : B
A. 0.46
B. 0.64
C. 0.78
D. 0.87
Answer : B
29. 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
A. Gauge pressure
B. Absolute pressure
C. Positive gauge pressure
D. Vacuum pressure
Answer : C
30. Free surface of a liquid behaves like a sheet and tends to contract to smallest possible area due to the
A. Force of adhesion
B. Force of cohesion
C. Force of friction
D. Force of diffusion
Answer : B
A. Force of adhesion
B. Force of cohesion
C. Force of friction
D. Force of diffusion
Answer : B
31. The length of a liquid stream while flowing over a weir __________ at the ends of the sill.
A. Expands
B. Does not change
C. Contracts
D. None of these
Answer : C
A. Expands
B. Does not change
C. Contracts
D. None of these
Answer : C
32. 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
A. 15.3 m
B. 25.3 m
C. 35.3 m
D. 45.3 m
Answer : A
33. Hydrometer is used to determine
A. Specific gravity of liquids
B. Specific gravity of solids
C. Specific gravity of gases
D. Relative humidity
Answer : A
A. Specific gravity of liquids
B. Specific gravity of solids
C. Specific gravity of gases
D. Relative humidity
Answer : A
34. A flow through a long pipe at decreasing rate is called __________ uniform flow.
A. Steady
B. Unsteady
C. Both A and B
D. None of these
Answer : B
A. Steady
B. Unsteady
C. Both A and B
D. None of these
Answer : B
35. A flow in which the quantity of liquid flowing per second is not constant, is called
A. Streamline flow
B. Turbulent flow
C. Steady flow
D. Unsteady flow
Answer : D
A. Streamline flow
B. Turbulent flow
C. Steady flow
D. Unsteady flow
Answer : D
36. Cavitation is caused by
A. High velocity
B. High pressure
C. Weak material
D. Low pressure
Answer : D
A. High velocity
B. High pressure
C. Weak material
D. Low pressure
Answer : D
37. The intensity of pressure at any point, in a liquid, is
A. Directly proportional to the area of the vessel containing liquid
B. Directly proportional to the depth of liquid from the surface
C. Directly proportional to the length of the vessel containing liquid
D. Inversely proportional to the depth of liquid from the surface
Answer : B
A. Directly proportional to the area of the vessel containing liquid
B. Directly proportional to the depth of liquid from the surface
C. Directly proportional to the length of the vessel containing liquid
D. Inversely proportional to the depth of liquid from the surface
Answer : B
38. 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
A. Open channel/pipe flow
B. Compressibility of fluids
C. Conservation of mass
D. Steady/unsteady flow
Answer : C
39. The meatcentric height of a ship is 0.6 m and the radius of gyration is 4 m. The time of rolling of a ship is
A. 4.1 s
B. 5.2 s
C. 10.4 s
D. 14.1 s
Answer : C
A. 4.1 s
B. 5.2 s
C. 10.4 s
D. 14.1 s
Answer : C
40. When the coefficient of discharge (Cd) is 0.623, then the general equation for discharge over a rectangular weir is
A. 1.84 (L - 0.1nH)H3/2
B. 1.84 (L - nH)H2
C. 1.84 (L - 0.1nH)H5/2
D. 1.84 (L - nH)H3
Answer : A
A. 1.84 (L - 0.1nH)H3/2
B. 1.84 (L - nH)H2
C. 1.84 (L - 0.1nH)H5/2
D. 1.84 (L - nH)H3
Answer : A
41. According to Manning's formula, the discharge through an open channel is (where M = Manning's constant)
A. A × M × m1/2 × i2/3
B. A × M × m2/3 × i1/2
C. A1/2 × M2/3 × m × i
D. A2/3 × M1/3 × m × i
Answer : B
A. A × M × m1/2 × i2/3
B. A × M × m2/3 × i1/2
C. A1/2 × M2/3 × m × i
D. A2/3 × M1/3 × m × i
Answer : B
42. The pressure of fluid due to hammer blow is
A. Directly proportional to density of fluid
B. Inversely proportional to density of fluid
C. Directly proportional to (density)1/2 of fluid
D. Inversely proportional to (density)1/2 of fluid
Answer : C
A. Directly proportional to density of fluid
B. Inversely proportional to density of fluid
C. Directly proportional to (density)1/2 of fluid
D. Inversely proportional to (density)1/2 of fluid
Answer : C
43. A large Reynold number is indication of
A. Smooth and streamline flow
B. Laminar flow
C. Steady flow br>D. Highly turbulent flow
Answer : D
A. Smooth and streamline flow
B. Laminar flow
C. Steady flow br>D. Highly turbulent flow
Answer : D
44. The Newton's law of resistance is based on the assumption that the
A. Planes of the body are completely smooth
B. Space around the body is completely filled with the fluid
C. Fluid particles do not exert any influence on one another
D. All of the above
Answer : D
A. Planes of the body are completely smooth
B. Space around the body is completely filled with the fluid
C. Fluid particles do not exert any influence on one another
D. All of the above
Answer : D
45. The property of a fluid which enables it to resist tensile stress is known as
A. Compressibility
B. Surface tension
C. Cohesion
D. Adhesion
Answer : C
A. Compressibility
B. Surface tension
C. Cohesion
D. Adhesion
Answer : C
46. The total pressure on a horizontally immersed surface is (where w = Specific weight of the liquid, A = Area of the immersed surface, and x = Depth of the centre of gravity of the immersed surface from the liquid surface)
A. wA
B. wx
C. wAx
D. wA/x
Answer : C
A. wA
B. wx
C. wAx
D. wA/x
Answer : C
47. When an internal mouthpiece is running free, the discharge through the mouthpiece is: (where a = Area of mouthpiece, and H = Height of liquid above the mouthpiece)
A. 0.5 a. ?2gH
B. 0.707 a. ?2gH
C. 0.855 a. ?2gH
D. a. ?2gH
Answer : A
A. 0.5 a. ?2gH
B. 0.707 a. ?2gH
C. 0.855 a. ?2gH
D. a. ?2gH
Answer : A
48. 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
A. Less than twice
B. More than twice
C. Less than three times
D. More than three times
Answer : C
49. 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
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
50. The pressure less than atmospheric pressure is known as
A. Suction pressure
B. Vacuum pressure
C. Negative gauge pressure
D. All of these
Answer : D
A. Suction pressure
B. Vacuum pressure
C. Negative gauge pressure
D. All of these
Answer : D
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