1000+ Fluid Mechanics MCQ for SSC CHSL [Solved]

1. 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

2. The property of fluid by virtue of which it offers resistance to shear is called
A. Surface tension
B. Adhesion
C. Cohesion
D. Viscosity
Answer : D

3. The value of coefficient of discharge is __________ the value of coefficient of velocity.
A. Less than
B. Same as
C. More than
D. None of these
Answer : A

4. The pressure measured with the help of a pressure gauge is called
A. Atmospheric pressure
B. Gauge pressure
C. Absolute pressure
D. Mean pressure
Answer : B

5. The velocity 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 : C

6. Reynold's number is the ratio of inertia force to
A. Pressure force
B. Elastic force
C. Gravity force
D. Viscous force
Answer : D

7. Newton's law of viscosity is a relationship between
A. Pressure, velocity and temperature
B. Shear stress and rate of shear strain
C. Shear stress and velocity
D. Rate of shear strain and temperature
Answer : B

8. The velocity at which the flow changes from laminar flow to turbulent flow is called
A. Critical velocity
B. Velocity of approach
C. Sub-sonic velocity
D. Super-sonic velocity
Answer : A

9. 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

10. A square surface 3 m × 3 m lies in a vertical line in water pipe its upper edge at water surface. The hydrostatic force on square surface is
A. 9,000 kg
B. 13,500 kg
C. 18,000 kg
D. 27,000 kg
Answer : B

11. Unit of surface tension is
A. Energy/unit area
B. Velocity/unit area
C. Both of the above
D. It has no units
Answer : A

12. The velocity 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

13. 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

14. Choose the wrong statement
A. Fluids are capable of flowing
B. Fluids conform to the shape of the containing vessels
C. When in equilibrium, fluids cannot sustain tangential forces
D. When in equilibrium, fluids can sustain shear forces
Answer : D

15. The coefficient of discharge for an external mouthpiece is
A. 0.375
B. 0.5
C. 0.707
D. 0.855
Answer : D

16. Resultant pressure of the liquid in the case of an immersed body acts through
A. Centre of gravity
B. Centre of pressure
C. Metacentre
D. Centre of buoyancy
Answer : B

17. In order to avoid tendency of separation at throat in a Venturimeter, the ratio of the diameter at throat to the diameter of pipe should be
A. 1/16 to 1/8
B. 1/8 to 1/4
C. 1/4 to 1/3
D. 1/3 to 1/2
Answer : D

18. 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

19. The unit of kinematic viscosity in S. I. units is
A. N-m/s
B. N-s/m²
C. m²/s
D. N-m
Answer : C

20. The specific gravity of water is taken as
A. 0.001
B. 0.01
C. 0.1
D. 1
Answer : D

21. 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

22. A vertical wall is subjected to a pressure due to one kind of liquid, on one of its sides. The total pressure on the wall per unit length is (where w = Specific weight of liquid, and H = Height of liquid)
A. wH
B. wH/2
C. wH²/2
D. wH²/3
Answer : C

23. 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

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

26. 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

27. 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

28. Bernoulli equation deals with the law of conservation of
A. Mass
B. Momentum
C. Energy
D. Work
Answer : C

29. 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

30. 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

31. A glass tube of smaller diameter is used while performing an experiment for the capillary rise of water because
A. It is easier to see through the glass tube
B. Glass tube is cheaper than a metallic tube
C. It is not possible to conduct this experiment with any other tube
D. All of the above
Answer : A

32. 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

33. 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

34. Coefficient of resistance is the ratio of
A. Actual velocity of jet at vena-contracta to the theoretical velocity
B. Area of jet at vena-contracta to the area of orifice
C. Loss of head in the orifice to the head of water available at the exit of the orifice
D. Actual discharge through an orifice to the theoretical discharge
Answer : C

35. Steady flow occurs when
A. The direction and magnitude of the velocity at all points are identical
B. The velocity of successive fluid particles, at any point, is the same at successive periods of time
C. The magnitude and direction of the velocity do not change from point to point in the fluid
D. The fluid particles move in plane or parallel planes and the streamline patterns are identical in each plane
Answer : B

36. 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

37. 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

38. 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

39. 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

40. 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

41. For a floating body to be in equilibrium
A. Meta centre should be above e.g.
B. Centre of buoyancy and e.g. must lie on same vertical plane
C. A righting couple should be formed
D. All of the above
Answer : D

42. The highest efficiency is obtained with a channel of __________ section.
A. Circular
B. Square
C. Rectangular
D. Trapezoidal
Answer : D

43. 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

44. 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

45. One cubic metre of water weighs
A. 100 litres
B. 250 litres
C. 500 litres
D. 1000 litres
Answer : D

46. An ideal flow of any fluid must satisfy
A. Pascal law
B. Newton's law of viscosity
C. Boundary layer theory
D. Continuity equation
Answer : D

47. 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

48. The increase of temperature results in
A. Increase in viscosity of gas
B. Increase in viscosity of liquid
C. Decrease in viscosity of gas
D. Decrease in viscosity of liquid
Answer : D

49. Water is a __________ fluid.
A. Real
B. Ideal
C. Newtonian
D. Non-Newtonian
Answer : C

50. 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