Fluid Mechanics MCQ Solved Paper for GMAT

1. Alcohol is used in manometers because
A. It has low vapour pressure
B. It is clearly visible
C. It has low surface tension
D. It can provide longer column due to low density
Answer : D

2. 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

3. A piece of metal of specific gravity 7 floats in mercury of specific gravity 13.6. What fraction of its volume is under mercury?
A. 0.5
B. 0.4
C. 0.515
D. 0.5
Answer : C

4. Viscous force is the __________ of shear stress due to viscosity and cross-section area of flow.
A. Sum
B. Different
C. Product
D. Ratio
Answer : C

5. 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

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

7. If the surface of liquid is convex, men
A. Cohesion pressure is negligible
B. Cohesion pressure is decreased
C. Cohesion pressure is increased
D. There is no cohesion pressure
Answer : C

8. The power transmitted through a pipe is (where w = Specific weight in N/m³, and Q = Discharge in m³/s)
A. w × Q × H
B. w × Q × hf
C. w × Q (H - hf)
D. w × Q (H + hf)
Answer : C

9. 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

10. If the coefficient of discharge is 0.6, then the discharge over a right angled notch is
A. 0.417 H^5/2
B. 1.417 H^5/2
C. 4.171 H^5/2
D. 7.141 H^5/2
Answer : B

11. The centre of gravity of the volume of the liquid displaced is called
A. Centre of pressure
B. Centre of buoyancy
C. Metacentre
D. None of these
Answer : B

12. For pipes, laminar flow occurs when Reynolds number is
A. Less than 2000
B. Between 2000 and 4000
C. More than 4000
D. Less than 4000
Answer : A

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

14. A notch is used to measure __________ of liquids.
A. Pressure
B. Discharge
C. Velocity
D. Volume
Answer : B

15. The most efficient section of a channel is
A. Triangular
B. Rectangular
C. Square
D. Trapezoidal
Answer : D

16. Whenever a plate is held immersed at some angle with the direction of flow of the liquid, it is subjected to some pressure. The component of this pressure, in the direction of flow of the liquid, is known as
A. Lift
B. Drag
C. Stagnation pressure
D. Bulk modulus
Answer : B

17. 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

18. 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

19. Bernoulli's equation is applied to
A. Venturimeter
B. Orifice meter
C. Pitot tube
D. All of these
Answer : D

20. 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

21. The ratio of the inertia force to the elastic force is called
A. Reynold's number
B. Froude's number
C. Weber's number
D. Mach number
Answer : D

22. The tangential velocity of the water element having a free vortex is
A. Directly proportional to its distance from the centre
B. Inversely proportional to its distance from the centre
C. Directly proportional to its (distance)² from the centre
D. Inversely proportional to its (distance)² from the centre
Answer : B

23. 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

24. 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

25. A flow whose streamline is represented by a straight line, is called __________ dimensional flow.
A. One
B. Two
C. Three
D. Four
Answer : A

26. The time oscillation of a floating body with increase in meatcentric height will be
A. Same
B. Higher
C. Lower
D. Lower/higher depending on weight of body
Answer : C

27. 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

28. The surface tension of mercury at normal temperature compared to that of water is
A. More
B. Less
C. Same
D. More or less depending on size of glass tube
Answer : A

29. The total energy line lies over the centre line of the pipe by an amount equal to
A. Pressure head
B. Velocity head
C. Pressure head + velocity head
D. Pressure head - velocity head
Answer : C

30. Dynamic viscosity of most of the liquids with rise in temperature
A. Increases
B. Decreases
C. Remain unaffected
D. Unpredictable
Answer : B

31. When a liquid is flowing through a pipe, the velocity of the liquid is
A. Maximum at the centre and minimum near the walls
B. Minimum at the centre and maximum near the walls
C. Zero at the centre and maximum near the walls
D. Maximum at the centre and zero near the walls
Answer : A

32. 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

33. The liquid used in manometers should have
A. Low density
B. High density
C. Low surface tension
D. High surface tension
Answer : D

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

35. 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

36. 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

37. An orifice is said to be large, if
A. The size of orifice is large
B. The velocity of flow is large
C. The available head of liquid is more than 5 times the height of orifice
D. The available head of liquid is less than 5 times the height of orifice
Answer : D

38. Gauge pressure at a point is equal to the absolute pressure __________ the atmospheric pressure.
A. Plus
B. Minus
C. Divide
D. Multiply
Answer : B

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

40. Piezometer is used to measure
A. Pressure in pipe, channels etc.
B. Atmospheric pressure
C. Very low pressures
D. Difference of pressure between two points
Answer : C

41. The Reynold's number of a ship is __________ to its velocity and length.
A. Directly proportional
B. Inversely proportional
C. Square root of velocity
D. None of these
Answer : A

42. 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

43. The intensity of pressure at any point, in a liquid, is __________ to the depth of liquid from the surface.
A. Equal
B. Directly proportional
C. Inversely proportional
D. None of these
Answer : B

44. The velocity of jet of water travelling out of opening in a tank filled with water is proportional to
A. Head of water (h)
B. h²
C. V/T
D. h/2
Answer : C

45. 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

46. Euler's number is the ratio of __________ force to pressure force.
A. Inertia
B. Gravity
C. Viscous
D. None of these
Answer : A

47. 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

48. A tank of uniform cross-sectional area (A) containing liquid upto height (H1) has an orifice of cross-sectional area (a) at its bottom. The time required to empty the tank completely will be
A. (2A?H?)/(C_d × a?2g)
B. (2AH?)/(C_d × a?2g)
C. (2AH?^3/2)/(C_d × a?2g)
D. (2AH?²)/(C_d × a?2g)
Answer : A

49. 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

50. 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