NMAT - Fluid Mechanics 1000+ MCQ [Solved] PDF Download

1. When the flow parameters at any given instant remain same at every point, then flow is said to be
A. Quasi-static
B. Steady state
C. Laminar
D. Uniform
Answer : D

2. 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

3. The coefficient of venturi-flume, generally, lies between
A. 0.3 to 0.45
B. 0.50 to 0.75
C. 0.75 to 0.95
D. 0.95 to 1.0
Answer : D

4. 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

5. In a forced vortex, the velocity of flow everywhere within the fluid is
A. Maximum
B. Minimum
C. Zero
D. Nonzero finite
Answer : D

6. 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

7. An open tank containing liquid is moving with an acceleration on an inclined plane. The inclination of the free surface of the liquid will be __________ to the acceleration of the tank.
A. Equal to
B. Directly proportional
C. Inversely proportional
D. None of these
Answer : B

8. 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

9. 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

10. 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

11. The loss of head at exit of a pipe is (where v = Velocity of liquid in the pipe)
A. v²/2g
B. 0.5v²/2g
C. 0.375v²/2g
D. 0.75v²/2g
Answer : A

12. The stress-strain relation of the Newtonian fluid is
A. Linear
B. Parabolic
C. Hyperbolic
D. Inverse type
Answer : A

13. The specific weight of water is 1000 kg/m3
A. At normal pressure of 760 mm
B. At 4°C temperature
C. At mean sea level
D. All the above
Answer : D

14. 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

15. 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

16. 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

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

18. 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

19. A liquid would wet the solid, if adhesion forces as compared to cohesion forces are
A. Less
B. More
C. Equal
D. Less at low temperature and more at high temperature
Answer : B

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

21. The pressure of liquid at throat in a Venturimeter is __________ than that at inlet.
A. Higher
B. Lower
C. Same
D. None of these
Answer : B

22. Rain drops are spherical because of
A. Viscosity
B. Air resistance
C. Surface tension forces
D. Atmospheric pressure
Answer : C

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

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

25. Falling drops of water become spheres due to the property of
A. Surface tension of water
B. Compressibility of water
C. Capillarity of water
D. Viscosity of water
Answer : A

26. 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

27. 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

28. According to Bernoulli's equation for steady ideal fluid flow
A. Principle of conservation of mass holds
B. Velocity and pressure are inversely proportional
C. Total energy is constant throughout
D. The energy is constant along a streamline but may vary across streamlines
Answer : D

29. The discharge over a rectangular notch is (where b = Width of notch, and H = Height of liquid, above the sill of the notch)
A. (2/3) C_d × b × ?(2gH)
B. (2/3) C_d × b × ?(2g) × H
C. (2/3) C_d × b × ?(2g) × H^3/2
D. (2/3) C_d × b × ?(2g) × H²
Answer : C

30. The resultant upward pressure of the fluid on an immersed body due to its tendency to uplift the submerged body is called
A. Up-thrust
B. Reaction
C. Buoyancy
D. Metacentre
Answer : C

31. 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

32. 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

33. The coefficient of discharge in case of internal mouthpiece is __________ that of external mouthpiece.
A. Less than
B. More than
C. Equal to
D. None of these
Answer : A

34. The mass 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 : B

35. The kinematic viscosity is the
A. Ratio of absolute viscosity to the density of the liquid
B. Ratio of density of the liquid to the absolute viscosity
C. Product of absolute viscosity and density of the liquid
D. Product of absolute viscosity and mass of the liquid
Answer : A

36. 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

37. A structure, whose width is __________ the width of the channel, is called a flumed structure.
A. Less than
B. More than
C. Equal
D. None of these
Answer : A

38. 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

39. The mass of 2.5 m3 of a certain liquid is 2 tonnes. Its mass density is
A. 200 kg/m³
B. 400 kg/m³
C. 600 kg/m³
D. 800 kg/m³
Answer : D

40. A metal with specific gravity of a floating in a fluid of same specific gravity a will
A. Sink to bottom
B. Float over fluid
C. Partly immersed
D. Be fully immersed with top surface at fluid surface
Answer : D

41. Two dimensional flows 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 : D

42. The power absorbed (in watts) in overcoming the viscous resistance of a footstep bearing is
A. ? ?³ N² R² /1800 t
B. ? ?³ N² R? /1800 t
C. ? ?³ N² R² /3600 t
D. ? ?³ N² R? /3600 t
Answer : B

43. The discharge in an open channel corresponding to critical depth is
A. Zero
B. Minimum
C. Maximum
D. None of thse
Answer : C

44. In a broad-crested weir, the discharge is maximum if the head of water on the downstream side of weir is __________ the head of water on the upstream side of weir.
A. Equal to
B. One-third
C. Two-third
D. Three-fourth
Answer : C

45. A flow in which each liquid particle has a definite path, and the paths of individual particles do not cross each other, is called
A. Steady flow
B. Uniform flow
C. Streamline flow
D. Turbulent flow
Answer : C

46. 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

47. A fluid is said to be ideal, if it is
A. Incompressible
B. Viscous and incompressible
C. Inviscous and compressible
D. Inviscous and incompressible
Answer : D

48. The variation in the volume of a liquid with the variation of pressure is called its
A. Surface tension
B. Compressibility
C. Capillarity
D. Viscosity
Answer : B

49. 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

50. Center of buoyancy is the
A. Centroid of the displaced volume of fluid
B. Center of pressure of displaced volume
C. Does not exist
D. None of the above
Answer : A