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These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Civil Engineering .

Chapters

Chapter: Flow Through Pipes

1. |
## The velocity corresponding to Reynold number of 2000 is called |

A. | Sub-sonic velocity |

B. | Super-sonic velocity |

C. | Lower critical velocity |

D. | Higher critical velocity |

Answer» C. Lower critical velocity |

2. |
## The loss of head at entrance in 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» B. 0.5v²/2g |

3. |
## Which of the following is an example of laminar flow? |

A. | Underground flow |

B. | Flow past tiny bodies |

C. | Flow of oil in measuring instruments |

D. | All of these |

Answer» D. All of these |

4. |
## The discharge over a rectangular weir, considering the velocity of approach, is (whereH1 = H + Ha = Total height of water above the weir, H = Height of water over the crest of the weir, and Ha = Height of water due to velocity of approach) |

A. | (2/3) Cd × L.√2g [H1 - Ha] |

B. | (2/3) Cd × L. √2g [H13/2 - Ha3/2] |

C. | (2/3) Cd × L.√2g [H12 - Ha2] |

D. | (2/3) Cd × L. √2g [H15/2 - Ha5/2] |

Answer» B. (2/3) Cd × L. √2g [H13/2 - Ha3/2] |

5. |
## The maximum efficiency of transmission through a pipe is |

A. | 50 % |

B. | 56.7 % |

C. | 66.67 % |

D. | 76.66 % |

Answer» C. 66.67 % |

6. |
## The efficiency of power transmission through pipe is (where H = Total supply head, and hf = Head lost due to friction in the pipe) |

A. | (H - hf )/H |

B. | H/(H - hf ) |

C. | (H + hf )/H |

D. | H/(H + hf ) |

Answer» A. (H - hf )/H |

7. |
## The hydraulic mean depth or the hydraulic radius is the ratio of |

A. | Area of flow and wetted perimeter |

B. | Wetted perimeter and diameter of pipe |

C. | Velocity of flow and area of flow |

D. | None of these |

Answer» A. Area of flow and wetted perimeter |

8. |
## The hydraulic mean depth for a circular pipe of diameter (d) is |

A. | d/6 |

B. | d/4 |

C. | d/2 |

D. | d |

Answer» B. d/4 |

9. |
## 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. Streamline flow |

10. |
## 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. Directly proportional |

11. |
## The velocity at which the laminar flow stops, is known as |

A. | Velocity of approach |

B. | Lower critical velocity |

C. | Higher critical velocity |

D. | None of these |

Answer» B. Lower critical velocity |

12. |
## The velocity corresponding to Reynold number of 2800, is called |

A. | Sub-sonic velocity |

B. | Super-sonic velocity |

C. | Lower critical velocity |

D. | Higher critical velocity |

Answer» D. Higher critical velocity |

13. |
## The total energy of a liquid particle in motion is equal to |

A. | Pressure energy + kinetic energy + potential energy |

B. | Pressure energy - (kinetic energy + potential energy) |

C. | Potential energy - (pressure energy + kinetic energy |

D. | Kinetic energy - (pressure energy + potential energy) |

Answer» A. Pressure energy + kinetic energy + potential energy |

14. |
## When a cylindrical vessel containing liquid is revolved about its vertical axis at a constant angular velocity, the pressure |

A. | Varies as the square of the radial distance |

B. | Increases linearly as its radial distance |

C. | Increases as the square of the radial distance |

D. | Decreases as the square of the radial distance |

Answer» A. Varies as the square of the radial distance |

15. |
## The length AB of a pipe ABC in which the liquid is flowing has diameter (d1) and is suddenly contracted to diameter (d2) at B which is constant for the length BC. The loss of head due to sudden contraction, assuming coefficient of contraction as 0.62, is |

A. | v₁²/2g |

B. | v₂²/2g |

C. | 0.5 v₁²/2g |

D. | 0.375 v₂²/2g |

Answer» D. 0.375 v₂²/2g |

16. |
## A large Reynold number is indication of |

A. | Smooth and streamline flow |

B. | Laminar flow |

C. | Steady flow |

D. | Highly turbulent flow |

Answer» D. Highly turbulent flow |

17. |
## 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√H₁)/(Cd × a√2g) |

B. | (2AH₁)/(Cd × a√2g) |

C. | (2AH₁3/2)/(Cd × a√2g) |

D. | (2AH₁²)/(Cd × a√2g) |

Answer» A. (2A√H₁)/(Cd × a√2g) |

18. |
## 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. Directly proportional to (radius)4 |

19. |
## For pipes, turbulent flow occurs when Reynolds number is |

A. | Less than 2000 |

B. | Between 2000 and 4000 |

C. | More than 4000 |

D. | Less than 4000 |

Answer» C. More than 4000 |

20. |
## The discharge through a siphon spillway is |

A. | Cd × a × √(2gH) |

B. | Cd × a × √(2g) × H3/2 |

C. | Cd × a × √(2g) × H2 |

D. | Cd × a × √(2g) × H5/2 |

Answer» A. Cd × a × √(2gH) |

21. |
## The shear stress-strain graph for a Newtonian fluid is a |

A. | Straight line |

B. | Parabolic curve |

C. | Hyperbolic curve |

D. | Elliptical |

Answer» A. Straight line |

22. |
## When a cylindrical vessel of radius (r) containing liquid is revolved about its vertical axis ω rad/s, then depth of parabola which the liquid assumes is |

A. | ω.r/2g |

B. | ω².r²/2g |

C. | ω.r/4g |

D. | ω².r²/4g |

Answer» B. ω².r²/2g |

23. |
## 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. Wake |

24. |
## The total pressure on the top of a closed cylindrical vessel of radius (r) completely filled up with liquid of specific weight (w) and rotating at (ω) rad/s about its vertical axis, is |

A. | π w ω² r²/4g |

B. | π w ω² r³/4g |

C. | π w ω² r⁴/4g |

D. | π w ω² r²/2g |

Answer» C. π w ω² r⁴/4g |

25. |
## The diameter of the nozzle (d) for maximum transmission of power is given by (where D = Diameter of pipe, f = Darcy’s coefficient of friction for pipe, and l = Length of pipe) |

A. | d = (D⁵/8fl)1/2 |

B. | d = (D⁵/8fl)1/3 |

C. | d = (D⁵/8fl)1/4 |

D. | d = (D⁵/8fl)1/5 |

Answer» C. d = (D⁵/8fl)1/4 |

26. |
## The fluid forces considered in the Navier Stokes equation are |

A. | Gravity, pressure and viscous |

B. | Gravity, pressure and turbulent |

C. | Pressure, viscous and turbulent |

D. | Gravity, viscous and turbulent |

Answer» A. Gravity, pressure and viscous |

27. |
## Select the wrong statement |

A. | An equivalent pipe is treated as an ordinary pipe for all calculations |

B. | The length of an equivalent pipe is equal to that of a compound pipe |

C. | The discharge through an equivalent pipe is equal to that of a compound pipe |

D. | The diameter of an equivalent pipe is equal to that of a compound pipe |

Answer» D. The diameter of an equivalent pipe is equal to that of a compound pipe |

28. |
## A flow through a long pipe at constant rate is called |

A. | Steady uniform flow |

B. | Steady non-uniform flow |

C. | Unsteady uniform flow |

D. | Unsteady non-uniform flow |

Answer» A. Steady uniform flow |

29. |
## 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. Critical velocity |

30. |
## 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. 4flv²/2gd |

31. |
## The loss of head due to viscosity for laminar flow in pipes is (where d = Diameter of pipe, l = Length of pipe, v = Velocity of the liquid in the pipe, μ = Viscosity of the liquid, and w = Specific weight of the flowing liquid) |

A. | 4μvl/wd² |

B. | 8μvl/wd² |

C. | 16μvl/wd² |

D. | 32μvl/wd² |

Answer» D. 32μvl/wd² |

32. |
## The loss of pressure head in case of laminar flow is proportional to |

A. | Velocity |

B. | (Velocity)2 |

C. | (Velocity)3 |

D. | (Velocity)4 |

Answer» A. Velocity |

33. |
## During the opening of a valve in a pipe line, the flow is |

A. | Steady |

B. | Unsteady |

C. | Uniform |

D. | Laminar |

Answer» B. Unsteady |

34. |
## The main property that affects a boundary layer is__________ |

A. | Temperature |

B. | Pressure |

C. | Viscosity |

D. | Surface tension |

Answer» C. Viscosity | |

Explanation: A boundary layer is an important concept that refers to the layer of fluid. The fluid that is in the immediate vicinity of a bounding surface. The main property that affects a boundary layer is viscosity. |

35. |
## The layer that is influenced by a planetary boundary is called______ |

A. | Atmospheric boundary layer |

B. | Lithosphere |

C. | Troposphere |

D. | Hydrosphere |

Answer» A. Atmospheric boundary layer | |

Explanation: The planetary boundary layer is also called as atmospheric boundary layer(ABL). It is the lowest part of the atmosphere. The behaviour of ABL is directly influenced by its contact with the planetary surface. |

36. |
## What is the other name for Stoke’s boundary layer? |

A. | Momentum boundary layer |

B. | Atmospheric boundary layer |

C. | Oscillatory boundary layer |

D. | Thermal boundary layer |

Answer» C. Oscillatory boundary layer | |

Explanation: Stoke’s boundary layer is also called as Oscillatory boundary layer. It is a boundary layer that is close to a solid wall. It moves in an oscillatory motion. It arrested by a viscous force acting in the opposite direction. |

37. |
## Eddy viscosity is a turbulent transfer of_________ |

A. | Fluid |

B. | Heat |

C. | Momentum |

D. | Pressure |

Answer» C. Momentum | |

Explanation: Eddy viscosity is a turbulent transfer of momentum by eddies. It gives rise to an internal fluid friction. It is in analogous to the action of molecular viscosity in laminar fluid flow. Eddy viscosity takes place on a large scale. |

38. |
## The laminar boundary layer is a _________ |

A. | Smooth flow |

B. | Rough flow |

C. | Uniform flow |

D. | Random flow |

Answer» A. Smooth flow | |

Explanation: For a laminar boundary layer the fluid moves in a very smooth flow. The laminar flow creates less skin friction drag. It is a less stable flow. The laminar boundary layer has got an increase in its thickness. |

39. |
## The turbulent boundary layer is a _________ |

A. | Non-uniform with swirls |

B. | Uniform |

C. | Less stable |

D. | Smooth |

Answer» A. Non-uniform with swirls | |

Explanation: For a turbulent boundary layer the fluid moves in different direction producing swirls. It has more skin friction drag than that of laminar boundary layer. It is more stable when compared to laminar. |

40. |
## How do we measure the flow rate of liquid? |

A. | Coriolis method |

B. | Dead weight method |

C. | Conveyor method |

D. | Ionization method |

Answer» A. Coriolis method | |

Explanation: Coriolis concept of measurement of fluid takes place through the rotation with the reference frame. It is an application of the Newton’s Law. The device continuously records, regulates and feeds large volume of bulk materials. |

41. |
## How does a turbulent boundary layer produce swirls? |

A. | Due to random motion |

B. | Collision of molecules |

C. | Due to eddies |

D. | Due to non-uniform cross section |

Answer» C. Due to eddies | |

Explanation: For a turbulent boundary layer the fluid moves in different direction producing swirls. It produces swirls due to the presence of eddies. The smooth laminar boundary layer flow breaks down and transforms to a turbulent flow. |

42. |
## Define Viscosity. |

A. | Resistance to flow of object |

B. | Resistance to flow of air |

C. | Resistance to flow of fluid |

D. | Resistance to flow of heat |

Answer» C. Resistance to flow of fluid | |

Explanation: Viscosity is developed due to the relative motion between two surfaces of fluids at different velocities. It happens due to the shear stress developed on the surface of the fluid. |

43. |
## How can we determine whether the flow is laminar or turbulent? |

A. | Reynold’s number |

B. | Mach number |

C. | Froude number |

D. | Knudsen number |

Answer» A. Reynold’s number | |

Explanation: Reynold’s number is used to determine whether the flow is laminar or turbulent. If Reynold’s number is less than 2000, it is a laminar flow. If Reynold’s number is greater than 2000, then it is a turbulent flow. |

44. |
## The flow separation occurs when the fluid travels away from the __________ |

A. | Surface |

B. | Fluid body |

C. | Adverse pressure gradient |

D. | Inter-molecular spaces |

Answer» C. Adverse pressure gradient | |

Explanation: Adverse pressure gradient takes place when the static pressure increases. It increases the direction of the flow. Adverse pressure gradient plays an important role in flow separation. Thus, option c is correct. |

45. |
## The swirl caused due to eddies are called as ______ |

A. | Vortices |

B. | Vertices |

C. | Volume |

D. | Velocity |

Answer» A. Vortices | |

Explanation: Vortices are a region in a fluid. It takes place when the flow revolves around an axis line. Vortices can be straight or curved. They form shapes like smoke rings and whirlpools. |

46. |
## Which among the following is a device that converts a laminar flow into a turbulent flow? |

A. | Dead Weight Gauge |

B. | Vacuum Gauge |

C. | Turbulator |

D. | Ionization Gauge |

Answer» C. Turbulator | |

Explanation: Turbulator is a device that converts a laminar flow into a turbulent flow. The turbulent flow can be desired parts of an aircraft or also in industrial applications. Turbulator is derived from the word “turbulent”. |

47. |
## With the boundary layer separation, displacement thickness________ |

A. | Increases |

B. | Decreases |

C. | Remains Same |

D. | Independent |

Answer» A. Increases | |

Explanation: With the boundary layer separation, displacement thickness increases sharply. This helps to modify the outside potential flow and its pressure field. Thus, option ‘a’ is the correct choice. |

48. |
## What is the instrument used for the automatic control scheme during the fluid flow? |

A. | Rotameters |

B. | Pulley plates |

C. | Rotary Piston |

D. | Pilot Static Tube |

Answer» D. Pilot Static Tube | |

Explanation: Pilot static tube is a system that uses an automatic control scheme to detect pressure. It has several holes connected to one side of the device. These outside holes are called as a pressure transducer, which controls the automatic scheme during fluid flow. |

49. |
## What is D’Alembert’s Paradox? |

A. | Resistance= 0 |

B. | Drag force= 0 |

C. | Temperature = 0 |

D. | Pressure gradient= 0 |

Answer» B. Drag force= 0 | |

Explanation: D’Alembert’s Paradox states that for an incompressible and inviscid flow potential flow, the drag force is equal to zero. The fluid is moving at a constant velocity with respect to its relative fluid. |

50. |
## The steady- state flow must satisfy ___________ |

A. | Kirchhoff’s law |

B. | Newtons law |

C. | Rutherford’s experiment |

D. | Kepler’s law |

Answer» A. Kirchhoff’s law | |

Explanation: The steady state flow must satisfy Kirchhoff’s first and second law. The first law states that the total flow into the junction equals the total flow away from the junction. Second law is called as the law of conservation of mass. It states that between two junctions, the head loss is independent of the path followed |

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