Quiznetik

Fluid Mechanics (FM) | Set 10

1. The flow rate of steam is controlled by regulating the_

Correct : B. Pressure

2. If Velocity, pressure, density etc., do not change at a point with respect to time, flow is called

Correct : D. steady

3. If velocity, pressure, density etc., change at a point with respect to time, flow is called

Correct : C. unsteady

4. If the velocity in a fluid flow does not change with respect to length of direction of flow, it is called

Correct : B. uniform flow

5. If the velocity in a fluid flow change with respect to length of direction of flow, it is called

Correct : D. none of the above

6. If the density of the fluid is constant from point to point in a flow region, it is called

Correct : B. incompressible flow

7. If the density of the flow changes from point to point in a flow region, it is called

Correct : D. compressible

8. Chezy’s Formula is given as

Correct : B. v= c √(rs)

9. The discharge through the trapezoidal channel is maximum when

Correct : A. half of the top width= sloping side

10. The maximum velocity through a circular channel when depth flow is equal to

Correct : C. 0.81 x diameter

11. The maximum discharge through a circular channel takes place when depth of flow is equal to

Correct : A. 0.95 x diameter

12. The most economical section is one for which a given cross sectional area, the slope of the bed (s) and coefficient of resistance has

Correct : B. maximum discharge

13. A hydraulically efficient trapezoidal section has a side slopes of 2 horizontal :1 vertical. The ratio of the bed width to depth B/y in this channel is

Correct : C. 0.472

14. al to 2m and 1m respectively. If the flow is uniform and the value of Chezy’s constant is 60, the discharge through the channel is

Correct : B. 1.5m3/s

15. A hydraulic jump takes place in a horizontal rectangular channel from a depth of 0.20m to 2.40m The discharge in the channel in m3/s per meter width is…

Correct : A. 2.47

16. A hydraulic jump occurs at the top of a spillway. The depth before jump is 0.2m. The sequent depth is 3.2m. What is the energy dissipated in m (approximate)?

Correct : B. 10.5

17. The hydraulic jump always occurs from

Correct : D. below critical depth to above critical depth

18. In a horizontal rectangular channel a hydraulic jump with a sequent depth ratio of 5.0 is formed. This jump can be classified as

Correct : B. oscillating jump

19. For a given discharge in a horizontal frictionless channel two depths may have the same specific force. These two depths are known as…

Correct : C. sequent depths

20. A turbine is a device, which converts

Correct : A. hydraulic energy into mechanical energy

21. An impulse turbine:

Correct : D. operates by initial complete conversion to kinetic head

22. An impulse turbine is installed

Correct : A. always above the tail race

23. A Pelton turbine is

Correct : D. all of the above

24. The reaction turbine is one in which the available hydraulic energy is converted to kinetic energy before the fluid enters the runner

Correct : B. partially

25. The function of draft tube is

Correct : C. both (a) and (b)

26. A draft tube is a part of the installation of a

Correct : A. propeller turbine

27. A turbine develops 3417hp at 240 r.p.m. The torque in the shaft is

Correct : D. 100kn.m

28. A reaction turbine discharges 50m3/sec of water under a head of 7.5m with an overall efficiency of 80%. The H.P. Developed is:

Correct : C. 4000

29. To generate 8.1 MW under a head of 81m while working at a speed of 540rpm, what type of turbine is suitable?

Correct : B. francis turbine

30. A turbine works at 20 m head and speed of 500 rpm. Its 1:2 scale model to be tested at same head should have a rotational speed of

Correct : D. 250rpm

31. The speed ratio of an impulse turbine operating under a head off 400m is 0.46. The p.c.d of turbine wheel is 22.25m then rotational speed, in rpm is

Correct : B. 346

32. Mechanical efficiency of a turbine is the ratio of

Correct : B. power at the shaft to the power given to the runner

33. The overall efficiency of the turbine is the ratio of

Correct : C. power at the shaft to the power at the inlet of turbine

34. The relation between hydraulic efficiency (ηh), mechanical efficiency (ηm) and overall efficiency (ηo) is

Correct : B. ??o= ??h x ??m

35. Specific speed of the turbine is defined as the speed at which the turbine runs when

Correct : B. working under unit head and develops unit horse power

36. The Unit speed is the speed of a turbine when it is working

Correct : C. under unit head

37. The ratio of actual work available at the turbine to the energy imparted to the wheel is known as _____________ efficiency.

Correct : B. mechanical

38. Which of the following turbine is preferred 0 to 25m head of water? P

Correct : B. kaplan turbine

39. A Francis turbine is used when the available head of water is

Correct : C. above 250m

40. The unit discharge through the turbine is

Correct : A. q/√h

41. The differential equation of the gradually varied flow can be written by using Manning’s Formula for the case off a wide rectangular channel as (dy/dx) =

Correct : A. s0{[1-(yn/y)3.33]/[1-(yn/y)3]}

42. If E = specific energy at a section in a gradually varied flow, then (dE/dx) =

Correct : B. s0-sf

43. ation Select the correct answer using the codes given below:

Correct : A. 1,2 and 3

44. Calculate the value of rate of change of specific energy for a triangular channel having depth 3.5m and the side slope is 1H:2V. Given: V=2.5m/s, dy/dx= 8.6x10-4

Correct : C. 5.47 x10-4m

45. Calculate the value of Sf for trapezoidal channel having depth 2m, width 5m and side slope of 1H:1.5V. Given: dy/dx= 1.18x10-3, S0= 1 in 1000, C= 50.

Correct : A. 0.00001

46. When S0 is equal to zero, it is called -----

Correct : B. horizontal slope

47. Hydraulic radius for wide rectangular channel section is---

Correct : C. y

48. Specific energy in GVF changes only under which of the following conditions:

Correct : A. difference between bed slope and slope of the energy line

49. When Yn is greater than Yc and So greater than 0, it is called as ----

Correct : D. mild

50. A slope based on the culvert bottom is called----

Correct : A. hydraulic slope

51. When S0 greater than 0 and Yn less than Yc it is called as

Correct : D. steep

52. Which of the following assumptions are true in case of GVF?

Correct : B. stream lines are parallel

53. What happens to depth of flow when there is obstruction in path

Correct : B. increases

54. Calculate the value of Froud’s number if the ratio of rate of change of specific energy and rate of change of depth is 0.9.

Correct : C. 0.31

55. If the difference between specific energies is 2m, calculate the rate of change of specific energies if the length of backwater curve is 26314 m.

Correct : B. 7.6 x10-5m

56. When gravitational force is equal to the friction drag, what type of depth is formed? P

Correct : B. normal depth

57. Determine the length of backwater curve if E1=2.8m, E2=5.6m, S0=0.00009, Sf= 0.00004.

Correct : D. 56000m

58. Calculate the bed slope of the channel if the slop of the energy line is 0.00024 and the length of backwater curve is 104166.67m. If E1-E2= 3m.

Correct : D. 5.28 x10-5

59. calculate the frictional slope of a triangular channel having depth 2.5m and side slope of 1H:2V. If the rate of change of specific energy is 1.6 x10-5m/s, If V= 1.57 m/s.

Correct : C. 7.53 x10-4m

60. The force exerted by jet of the water on stationary vertical plate in the direction of the jet is given by

Correct : C. fx= ??av2

61. The force exerted by jet of the water on stationary inclined plate in the direction of the jet is given by

Correct : B. fx= ??av2sin2??

62. The force exerted by jet of the water on stationary curved plate in the direction of the jet is given by

Correct : B. fx = ??av2(1+cos??)

63. The force exerted by jet of the water having velocity V on a vertical plate moving with a velocity u is given by

Correct : B. fx = ??a(v-u) 2

64. The force exerted by jet of the water having velocity V on a series of vertical plate moving with a velocity u is given by,

Correct : A. fx= ??av2.

65. Efficiency of the jet of the water having velocity V & Striking a series if vertical plates moving with a velocity u is given by,

Correct : B. [2u(v-u)]/v2

66. Efficiency off the jet of the water having velocity V & Striking a series of vertical plates moving with a velocity u, is maximum when

Correct : D. none of the above

67. For a series o curved radial vanes, the work done per second per unit weight is equal to

Correct : C. 1/g[vw1u1??vw2u2.]

68. The work done by centrifugal pump on water per second per unit weight of water is given by

Correct : B. 1/g[vw2u2]

69. The manometric head Hm of a centrifugal pump is given by

Correct : C. total head at outlet - total head at inlet

70. The manometric efficiency (ηman) of a centrifugal pump is given by

Correct : B. ghm/vw2u2

71. Mechanical efficiency (ηmech) of a centrifugal pump is given by

Correct : A. (power at the impeller)/ s.h.p.

72. To produce a high head by multistage centrifugal pumps, the impellers are connected… P

Correct : B. in series

73. To discharge a large quantity of liquid by multi-stage centrifugal pump, the impellers are connected

Correct : A. in parallel

74. Specific speed of a pump is the speed at which a pump runs when

Correct : A. head developed is unity and discharge is one cubic meter

75. The specific speed (Ns) of aa pump is given by thee expression

Correct : C. ns= [n√q]/[hm3/4]

76. Cavitation will take place if the pressure of the flowing fluid at any point is P

Correct : C. is less than vapor pressure of the fluid

77. Cavitation can take place in case of

Correct : B. francis turbine

78. Air vessel in reciprocating pump is used

Correct : A. to obtain continuous supply of water at uniform rate

79. During suction stroke of a reciprocating pump, the separation may take place

Correct : C. in the beginning of the suction stroke

80. During delivery stroke of a reciprocating pump, the separation may take place P

Correct : A. ge 5 of 7a) at the end of the suction stroke

81. 14 Discharge of centrifugal pump is

Correct : C. directly proportional to (diameter)2 of its impeller

82. The ratio of quantity off liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as

Correct : D. volumetric efficiency

83. Multi-stage centrifugal pump are used to

Correct : B. produce high heads

84. The specific speed of a centrifugal pump, delivering 750 liters of water per second against a head of 15 meters at 725r.p.m., is

Correct : C. 82.4r.p.m.

85. The specific speed from a centrifugal pump indicates that the pump is

Correct : D. high speed with axial flow at outlet

86. Discharge of a centrifugal pump is (where N= speed of the pump impeller)

Correct : A. directly proportional to n

87. For a centrifugal pump impeller, the maximum value of the vane exit angle is

Correct : C. 20o to 25o

88. Pascal-second is the unit of

Correct : C. dynamic viscosity

89. An ideal fluid is

Correct : B. frictionless and incompressible

90. The unit of kinematic viscosity is

Correct : D. cm2/sec

91. If the dynamic viscosity of a fluid is 0.5 poise and specific gravity is 0.5, then the kinematic viscosity of that fluid in stokes is

Correct : C. 1.0

92. The viscosity of a gas

Correct : B. increases with increase in temperature

93. Newton’s law of viscosity relates

Correct : B. shear stress and rate of angular deformation

94. An open tank contains 1 m deep water with 50 cm depth of oil of specific gravity 0.8 above it. The intensity of pressure at the bottom of tank will be

Correct : D. 14 kN/m2

95. The position of center of pressure on a plane surface immersed vertically in a static mass of fluid is

Correct : C. always below the centroid of the area

96. The total pressure on a plane surface inclined at an angle 9 with the horizontal is equal to (where p is pressure intensity at centroid of area and A is area of plane surface.)

Correct : A. PA

97. A vertical rectangular plane surface is submerged in water such that its top and bottom surfaces are 1.5 m and 6.0 m res-pectively below the free surface. The position of center of pressure below the free surface will be at a distance of

Correct : C. 4.2m

98. Centre of buoyancy always

Correct : B. coincides with the centroid of the volume of fluid displaced

99. If the weight of a body immersed in a fluid exceeds the buoyant force, then the body will

Correct : B. tend to move downward and it may finally sink

100. Metacentric height for small values of angle of heel is the distance between the

Correct : B. centre of gravity and metacentre