Fluid Mechanics 1000+ MCQ with answer for SSC JE

1. All the terms of energy in Bernoulli's equation have dimension of
A. Energy
B. Work
C. Mass
D. Length
Answer : D

2. 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

3. Total pressure on a lmxlm gate immersed vertically at a depth of 2 m below the free water surface will be
A. 1000 kg
B. 4000 kg
C. 2000 kg
D. 8000 kg
Answer : A

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. The bulk modulus of elasticity with increase in pressure
A. Increases
B. Decreases
C. Remain constant
D. Increases first up to certain limit and then decreases
Answer : A

6. 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

7. Bulk modulus of a fluid is the ratio of
A. Shear stress to shear strain
B. Increase in volume to the viscosity of fluid
C. Increase in pressure to the volumetric strain
D. Critical velocity to the viscosity of fluid
Answer : C

8. The total pressure on the top of a closed cylindrical vessel completely filled up with a liquid is
A. Directly proportional to (radius)²
B. Inversely proportional to (radius)²
C. Directly proportional to (radius)⁴
D. Inversely proportional to (radius)⁴
Answer : C

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

10. 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

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

12. In an internal mouthpiece, the absolute pressure head at vena contracta is __________ the atmospheric pressure head by an amount equal to height of the liquid above the vena contracta.
A. Less than
B. More than
C. Equal to
D. None of these
Answer : A

13. 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

14. A streamline is defined as the line
A. Parallel to central axis flow
B. Parallel to outer surface of pipe
C. Of equal velocity in a flow
D. Along which the pressure drop is uniform
Answer : C

15. Which of the following is the unit of kinematic viscosity?
A. Pascal
B. Poise
C. Stoke
D. Faraday
Answer : C

16. 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

17. 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

18. The discharge over a right angled notch is (where H = Height of liquid above the apex of notch)
A. (8/15) C_d. 2g. H
B. (8/15) C_d. 2g. H^3/2
C. (8/15) C_d. 2g. H²
D. (8/15) C_d. 2g. H^5/2
Answer : D

19. The discharge over a triangular 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 : D

20. The ratio of absolute viscosity to mass density is known as
A. Specific viscosity
B. Viscosity index
C. Kinematic viscosity
D. Coefficient of viscosity
Answer : C

21. A flow in which __________ force is dominating over the viscosity is called turbulent flow.
A. Elastic
B. Surface tension
C. Viscous
D. Inertia
Answer : D

22. The Cipoletti weir is a __________ weir.
A. Rectangular
B. Triangular
C. Trapezoidal
D. Circular
Answer : C

23. A channel is said to be of most economical cross-section, if
A. It gives maximum discharge for a given cross-sectional area and bed slope
B. It has minimum wetted perimeter
C. It involves lesser excavation for the designed amount of discharge
D. All of the above
Answer : D

24. Property of a fluid by which its own molecules are attracted is called
A. Adhesion
B. Cohesion
C. Viscosity
D. Compressibility
Answer : B

25. If a body floating in a liquid occupies a new position and remains at rest in this new position, when given a small angular displacement, the body is said to be in __________ equilibrium.
A. Neutral
B. Stable
C. Unstable
D. None of these
Answer : A

26. An open vessel of water is accelerated up an inclined plane. The free water surface will
A. Be horizontal
B. Make an angle in direction of inclination of inclined plane
C. Make an angle in opposite direction to inclination of inclined plane
D. Any one of above is possible
Answer : C

27. In an external mouthpiece, the absolute pressure head at vena contracta is __________ the atmospheric pressure head by an amount equal to 0.89 times the height of the liquid, above the vena contracta.
A. Less than
B. More than
C. Equal to
D. None of these
Answer : A

28. 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

29. Surface tension has the units of
A. Newton-sec/m
B. Newton-m/sec
C. Newton/m
D. Newton
Answer : C

30. A flow through an expanding tube at constant rate is called
A. Steady uniform flow
B. Steady non-uniform flow
C. Unsteady uniform flow
D. Unsteady non-uniform flow
Answer : B

31. The bulk modulus of elasticity
A. Has the dimensions of 1/pressure
B. Increases with pressure
C. Is large when fluid is more compressible
D. Is independent of pressure and viscosity
Answer : B

32. A hemispherical tank of radius (R) has an orifice of cross-sectional area (a) at its bottom and is full of liquid. The time required to empty the tank completely is
A. 14? R^1/2/15C_d × a ?(2g)
B. 14? R^3/2/15C_d × a ?(2g)
C. 14? R^5/2/15C_d × a ?(2g)
D. 14? R^7/2/15C_d × a ?(2g)
Answer : C

33. An air vessel is provided at the summit in a siphon to
A. Avoid interruption in the flow
B. Increase discharge
C. Increase velocity
D. Maintain pressure difference
Answer : A

34. For a floating body to be in stable equilibrium, its metacentre should be
A. Below the center of gravity
B. Below the center of buoyancy
C. Above the center of buoyancy
D. Above the center of gravity
Answer : D

35. According to the principle of buoyancy a body totally or partially immersed in a fluid will be lifted up by a force equal to
A. The weight of the body
B. More than the weight of the body
C. Less than the weight of the body
D. Weight of the fluid displaced by the body
Answer : D

36. 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

37. Coefficient of discharge Cd is equal to (where Cc = Coefficient of contraction, Cv = Coefficient of velocity, and Cr = Coefficient of resistance)
A. Cc × Cv
B. Cc × Cr
C. Cv × Cr
D. Cc/Cr
Answer : A

38. A piece weighing 3 kg in air was found to weigh 2.5 kg when submerged in water. Its specific gravity is
A. 1
B. 5
C. 7
D. 6
Answer : D

39. 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

40. The maximum discharge over a broad crested weir is
A. 0.384 C_d × L × H^1/2
B. 0.384 C_d × L × H^3/2
C. 1.71 C_d × L × H^1/2
D. 1.71 C_d × L × H^3/2
Answer : D

41. 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

42. 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

43. The stability of a dam is checked for
A. Tension at the base
B. Overturning of the wall or dam
C. Sliding of the wall or dam
D. All of these
Answer : D

44. The viscosity of water is __________ than that of mercury.
A. Higher
B. Lower
C. Same as
D. None of these
Answer : A

45. Mercury is often used in barometer because
A. It is the best liquid
B. The height of barometer will be less
C. Its vapour pressure is so low that it may be neglected
D. Both (B) and (C)
Answer : D

46. 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

47. Choose the wrong statement
A. Any weight, floating or immersed in a liquid, is acted upon by a buoyant force
B. Buoyant force is equal to the weight of the liquid displaced
C. The point through which buoyant force acts, is called the center of buoyancy
D. Center of buoyancy is located above the center of gravity of the displaced liquid
Answer : D

48. When the water level on the downstream side of a weir is above the top surface of a weir, the weir is known as
A. Narrow-crested weir
B. Broad-crested weir
C. Ogee weir
D. Submerged weir
Answer : D

49. The unit of dynamic viscosity in S.I. units is
A. N-m/s²
B. N-s/m²
C. Poise
D. Stoke
Answer : B

50. Choose the wrong statement
A. Viscosity of a fluid is that property which determines the amount of its resistance to a shearing force
B. Viscosity is due primarily to interaction between fluid molecules
C. Viscosity of liquids decreases with increase in temperature
D. Viscosity of liquids is appreciably affected by change in pressure
Answer : D