CHAPTER 11 – FLUID MECHANICS
1. If the energy of the incident photon is less than the work function:
A. an electron will be ejected
B. more than one electron will be ejected
C. an electron will not be ejected
D. less than one electron will be ejected
Answer: C
2. For supersonic flow, the pressure of fluid must decrease at the flow area of the duct.
A. increases
B. decreases
C. remain the same
D. none of these
Answer: A
3. Density in terms of viscosity is:
A. kinematic viscosity / dynamic viscosity
B. dynamic viscosity / kinematic viscosity
C. kinematic viscosity x dynamic viscosity
D. none of the above
Answer: B
4. Liquids and gasses take the following characteristics of their contents.
A. Volume
B. Shape
C. Shape and volume
D. Neither shape nor volume
Answer: B
5. Alcohol finds use in manometer as:
A. it provides a suitable meniscus for the inclined tube
B. its density being less can provide longer length for a pressure difference, thus more accuracy
can be obtained
C. A and B above are correct
D. Cheap and easily available
Answer: C
6. Which of the following statements about a Newtonian fluid is most accurate?
A. Shear stress is proportional to strain
B. Viscosity is zero
C. Shear stress is multi-valued
D. Shear stress is proportional to rate of strain
Answer: D
7. The normal stress is the same in all directions at a point in fluid:
A. independent of the motion of one fluid layer relative to an adjacent layer
B. when there is no motion of one fluid layer relative to an adjacent layer
C. only if the fluid is frictionless
D. only if fluid is frictionless and incompressible
Answer: B
8. Which of the following is not a characteristic of fluid pressure?
A. it is the same in all directions at a point in the fluid
B. it acts normal to a surface
C. it is a shear stress
D. it is linear width depth
Answer: C
9. The length of mercury column at a place at an altitude will change with respect to that at
ground in:
A. a linear relation
B. a parabolic relation
C. will remain constant
D. first slowly and then steeply
Answer: D
10. All of the following dimensionless parameters are applicable to fluid flow except
the________.
A. Reynolds number
B. Froude number
C. Mach number
D. Biot number
Answer: D
11. Mass density of liquid (P) is given by which of the following?
A. P = mass/volume
B. P = metric slug/m2
C. P = kg sec2/m4
D. all of the above
Answer: D
12. The speed of sound in all fluid is most closely related all of the following properties except
_________.
A. compressibility
B. density
C. bulk modulus
D. thermal conductivity
Answer: D
13. Under which condition, the specific weight of water is 1000 kg/m3?
A. at normal pressure of 760 mm
B. at 4 deg. Celcius temperature
C. at mean sea level
D. all of the above
Answer: D
14. All of the following can be characteristics of fluids except _________.
A. kinematic viscosity
B. surface tension
C. bulk modulus
D. hysteresis
Answer: D
15. Which of the following can be used to measure the flow of water in a pipe of diameter 3000
mm?
A. Venturimeter
B. Rotameter
C. Nozzle
D. Pitot tube
Answer: D
16. The pressure at a given depth due to several immiscible liquids is:
A. the average of the individual pressures
B. the sum of the individual pressures
C. independent of the individual pressures
D. unknown
Answer: B
17. The equation of continuity of flow is applicable if:
A. the flow is one dimensional
B. the flow is steady
C. the velocity is uniform over the cross-section
D. all of the above conditions are together
Answer: D
18. Uniform flow takes place when:
A. conditions remain unchanged with time at any point
B. rate of change of velocity of fluid is zero
C. at every point the velocity vector is identical in magnitude and direction for any given instant
D. the change in transverse direction is zero
Answer: C
19. The continuity equation of an ideal fluid flow:
A. states that the net rate of in – flow into any small volume must be zero
B. applies to irrotational flow only
C. states that the energy remains constant along streamline
D. states that energy is constant everywhere in the fluid
Answer: D
20. A pitot tube can be used to measure fluid velocity as described by the Bernoulli‟s equation
and the relationship between:
A. kinetic energy and static pressure
B. fluid pressure and height of the fluid
C. fluid pressure and impact energy
D. pressure and momentum
Answer: A
21. In order to avoid vaporization in the pipe line, the pipe line over the ridge is laid in such a
way that it is not more than:
A. 2.4 m above the hydraulic gradient
B. 6.4 m above the hydraulic gradient
C. 10.0 m above the hydraulic gradient
D. 5.0 above the hydraulic gradient
Answer: B
22. The stream function is a useful parameter in describing __________.
A. the conservation of mass
B. the conservation of momentum
C. the conservation of energy
D. the equation of state
Answer: A
23. For high speed flows, the potential energy of the fluids are:
A. positive
B. negative
C. negligible
D. none of these
Answer: C
24. McLeod gauge used for low pressure measurement operates on the principle of _________.
A. Gas law
B. Boyle‟s law
C. Charles law
D. Pascal‟s law
Answer: B
25. A Kaplan turbine is:
A. a high head mixed flow turbine
B. an Impulse turbine, inward flow
C. a reaction tube, outward flow
D. low head axial low turbine
Answer: D
26. The most common method for calculating frictional energy loss for laminar flowing in
noncircular pipes is:
A. the Darcy equation
B. the Hagan – Poisevill equation
C. the Hazen – Williams equation
D. the Swamee – Jin equation
Answer: A
27. The parameter f in the expression for the head-loss is:
A. the fraction of flow that is totally turbulent
B. the Darcy friction factor
C. the height of the roughness scale in turbulent flow
D. the static coefficient of friction
Answer: B
28. Friction factor both laminar and turbulent flows can be found plotted in a:
A. steam table
B. psychometric chart
C. Moody diagram
D. Mollier diagram
Answer: C
29. Which of the following is relative velocity?
A. The difference between the two velocities
B. Average velocity
C. Sum of two velocities
D. Vector difference of two velocities
Answer: D
30. Which of the following is the highest head?
A. 33 inch Hg
B. 31.0 ft. water
C. 1.013 kg kg/cm2
D. 75.0 cm of Hg
Answer: A
31. For stable equilibrium of floating body its metacenter should lie:
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
32. Center of pressure on an inclined plane lies _____.
A. at the centroid
B. above the centroid
C. below the centroid
D. at metacenter
Answer: C
33. The line of action of the buoyant forces always acts through the centroid of the __________.
A. submerged body
B. volume of the floating body
C. volume of the fluid vertically above the body
D. displaced volume of the fluid
Answer: D
34. The hydraulic grade line of a pipeline denotes which of the following?
A. Total energy
B. Pressure energy
C. Potential energy
D. The sum pressure energy and potential energy
Answer: D
35. The energy grade line of a pipeline denotes which if the following?
A. Total energy
B. Pressure energy
C. Potential energy
D. The sum of pressure energy and potential energy
Answer: A
36. The presence of friction in the energy grade line will always cause the line to slope
A. down in the direction of the flow
B. upward in the direction of the flow
C. level (no slope)
D. there is no effect of friction on the energy grade line
Answer: A
37. The pitot tube is a device used for measurement of
A. pressure
B. flow
C. velocity
D. discharge
Answer: C
38. Hydrometer is used to find out
A. specific gravity of liquids
B. specific gravity of solids
C. specific gravity of gasses
D. relative humidity
Answer: A
39. The fluid forces taken into consideration 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
40. Permissible velocity of water flowing through concrete tunnel, is generally
A. 4 – 5 m/s
B. 10 – 12 m/s
C. 13 – 16 m/s
D. 20 m/s
Answer: A
41. Orifice refers to an opening
A. with closed perimeter and of regular form through which water flow
B. with prolonged sides having length of 2to 3 diameters of opening in thick wall
C. with partially full flow
D. in hydraulic structure with regulation provision
Answer: D
42. The value of coefficient of discharge in comparison to coefficient of velocity is found to be
__________.
A. more
B. less
C. same
D. more/less depending on flow
Answer: B
43. Weir is refer to an opening
A. having closed perimeter and of regular form through which water flow
B. having prolonged sides with length of 2 to 3 diameters of opening in thick wall
C. having partially full flow
D. in hydraulic structure with regulation provision
Answer: C
44. Which of the following parameters determine the friction factor of turbulent flow in a rough
pipe?
A. Froude number and relative roughness
B. Froude number and Mach number
C. Reynolds number and relative roughness
D. Mach number and relative roughness
Answer: C
45. Power transmitted through a pipe is maximum when the loss of head due to friction is:
A. one-half of total head supplied
B. one-third of the total head supplied
C. one-fourth of the total head supplied
D. equal to the total head supplied
Answer: B
46. In a nozzle if back pressure is same as inlet pressure; then _______.
A. no flow takes place
B. maximum flow takes place
C. flow becomes subsonic in diverging section
D. flow becomes supersonic in converging as well as supersonic section
Answer: A
47. The flow on two sides of a normal shock wave is called ___________.
A. sonic
B. sub – sonic
C. supersonic
D. supersonic on one side and sub – sonic on the other side
Answer: D
48. Which of the following is the basic of Bernoulli‟s law for fluid flow?
A. Continuity equation
B. Principle of conservation of energy
C. Fourier‟s law
D. Principle of conservation of mass
Answer: B
49. Which of the following is NOT a characteristic of fluid pressure?
A. It is a shear stress
B. It is the same in all directions at a point in the fluid
C. It acts normal to a surface
D. It is linear with depth
Answer: A
50. Refers to the compressibility of a fluid, the fractional change in fluid volume per unit change
in fluid.
A. Viscosity
B. Bulk modulus
C. Density
D. Pressure
Answer: D
51. A pitot tube can be used to measure fluid velocity as described by the Bernoulli equation and
the relationship between:
A. kinetic energy and static pressure
B. fluid pressure and static pressure
C. fluid pressure and impact energy
D. pressure and momentum
Answer: A
52. The ratio of the area to the wetted perimeter is known as __________.
A. flow factor
B. hydraulic radius
C. Kutter‟s C
D. value of k in Darcy – Weisbach formula
Answer: B
53. What is the coefficient of contraction?
A. The ratio of the area of vena contracta to the area of the orifice
B. The ratio of actual discharge to the theoretical discharge
C. The ratio of the actual velocity to the theoretical velocity
D. The ratio of the effective head to the actual head
Answer: A
54. Where is vena contracta most likely located?
A. At the orifice
B. At a distance approximately ½ the diameter of the orifice
C. At a distance approximately equal to the diameter of the orifice
D. At a distance approximately twice the diameter of the orifice
Answer: B
55. A substance that s able to flow and yields to any force tending to change its shape without
changing its volume such as water and air.
A. Fluid
B. Flux
C. Gas oil
D. Water gas
Answer: A
56. The velocity of a fluid particle at the center of the pipe section is __________.
A. maximum
B. minimum
C. average
D. logarithmic average
Answer: A
57. For supersonic flow, the pressure of fluid must increase as the fluid flow area of the duct;
A. increases
B. decreases
C. constant
D. none of these
Answer: B
58. Which is incorrect statement regarding apparent shear force.
A. It can never be found in frictionless fluid regardless of its motion
B. It can never be found when the fluid is at rest
C. It depends upon cohesive forces
D. It may occur owing to cohesion when the fluid is at rest
Answer: D
59. The time required for half a quantity of radioactive particles to decay (disintegrate) is called
its _________.
A. average life
B. median life
C. time constant
D. half time
Answer: D
60. SI unit of viscosity is:
A. 10 times poise
B. 9.81 times poise
C. 1/9.81 times poise
D. 1/10 times poise
Answer: A
61. For computation convenience, fluids are usually classed as:
A. rotational or irrotational
B. real or ideal
C. laminar or turbulent
D. Newtonian or non-Newtonian
Answer: B
62. Which of the following is not a dimensionless parameter?
A. kinetic viscosity
B. Weber number
C. Darcy Weisbach friction factor
D. Froude number
Answer: A
63. Which of the following is not a characteristic of real fluid?
A. Finite viscosity
B. Non – uniform velocity distribution
C. Compressibility
D. Experience of eddy currents and turbulence
Answer: D
64. Which of the following is not the mass density of water?
A. 62.5 lbm/ft3
B. 100 kg/m3
C. 1 g/cm3
D. 1 kg/L
Answer: B
65. The upper critical Reynolds number for pipe flow is:
A. of no practical importance to designers
B. always used to design pipes for strength
C. the number at which turbulent flow changes over to laminar flow
D. the number at which laminar flow changes into turbulent flow
Answer: A
66. Which of the following statements about gauge pressure is most correct? Gauge pressure are
measured relative to __________.
A. atmospheric pressure
B. a vacuum
C. each other
D. the surface
Answer: A
67. The volumetric change of the fluid caused by a resistance is called ___________.
A. volumetric strain
B. volumetric index
C. compressibility
D. adhesion
Answer: D
68. Compressibility of a fluid relates the fractional change in fluid volume per unit change in
fluid.
A. temperature
B. density
C. pressure
D. viscosity
Answer: C
69. Property of a fluid whereby its own molecules are attracted is known as __________.
A. adhesion
B. cohesion
C. surface tension
D. viscosity
Answer: B
70. The term subsonic flow refers to the flowing gas with a speed:
A. less than the local speed of sound
B. equal to the speed of sound
C. greater than the speed of sound
D. much greater than the speed of sound
Answer: A
71. The pressure at a point in a fluid will not be same in all the directions if the fluid is:
A. viscous
B. viscous and static
C. inviscous and in motion
D. viscous and is in motion
Answer: D
72. The statement that “the hydrostatic pressure a fluid exerts on an immersed object or on
container walls is a function only of fluid depth” is
A. the perfect gas law
B. D‟Alembert‟s paradox
C. the hydrostatic paradox
D. Boyle‟s law
Answer: C
73. Bernoulli‟s equation is/an __________.
A. momentum equation
B. conservation of energy equation
C. conservation of mass equation
D. equation of state
Answer: B
74. An ideal fluid is one that:
A. is very viscous
B. obeys Newton‟s law of viscosity
C. is assumed in problems in conduit flow
D. is frictionless and incompressible
Answer: D
75. The relationship between pressure and altitude in the atmosphere is given by the:
A. perfect gas law
B. conservation of mass
C. barometric height relationship
D. first law of thermodynamics
Answer: C
76. The fact the buoyant force on a floating object equal to the weight of the water displaced is:
A. Bernoulli‟s law
B. Archimedes‟ principle
C. The law of diminishing returns
D. The conservation of mass
Answer: B
77. Which of the following terms dos not appear in the steady flow energy equation (the
extended Bernoulli‟s equation)?
A. Kinetic energy
B. Potential energy
C. Friction losses
D. Hysteresis losses
Answer: D
78. Neglecting the forces due to inertia, gravity and frictional resistance, the design of a channel
can be made by comparing
A. Weber number
B. Reynolds number
C. Froude number
D. Prant‟l number
Answer: C
79. The difference between stagnation pressure and total pressure is:
A. due to height difference
B. due to fluid kinetic energy
C. none of the terms are interchangeable
D. important only in supersonic flow
Answer: C
80. Fully turbulent flow in a pipe is characterized by all of the following except:
A. a parabolic velocity profile
B. a momentum exchange due to fluid masses rather than molecules
C. a maximum velocity at the fluid center line
D. a 1/7 velocity profile
Answer: A
81. The laminar flow factor of fluid flowing through a pipe is function of all of the following
except:
A. fluid velocity
B. pipe diameter
C. pipe roughness
D. Reynolds number
Answer: C
82. The continuity equation is applicable to:
A. viscous unviscous fluids
B. compressibility of fluids
C. conservation of mass
D. steady unsteady flow
Answer: C
83. The rise or fall of head „h‟ in a capillary tube of diameter „d‟ and liquid surface tension „s‟
and specific weight „w‟ is given by:
A. 4s/wd
B. 4ds/w
C. 4wd/s
D. 4ws/d
Answer: A
84. The study of the practical laws of fluid flow and the resistance of open pipes and channels.
A. fluid mechanics
B. hydraulics
C. aerodynamics
D. thermodynamics
Answer: B
85. Which of the following turbine is different from the others?
A. Fourneyron turbine
B. Francis turbine
C. Kaplan turbine
D. Pelton wheel
Answer: D
86. Running away speed of a Pelton wheel gives:
A. actual operating speed
B. no load speed
C. full load speed
D. no load speed when governor mechanism fails
Answer: D
87. Which of the following turbine is different from the others?
A. Pelton wheel
B. Banki turbine
C. Jonval turbine
D. Kaplan turbine
Answer: D
88. The characteristic length of the Reynold‟s number used to calculate the friction in
noncircular full running pipes is based on the __________.
A. run length
B. pipe length
C. hydraulic diameter (the equivalent diameter)
D. wetted circumference
Answer: C
89. The hydraulic radius of noncircular pipe is:
A. the square root of the flow area
B. the ratio of the area to the wetted perimeter
C. the radius of a pipe of equivalent area
D. none of the above
Answer: B
90. The Darcy equation can be used for all liquid and flow except:
A. water
B. alcohol
C. gasoline
D. air flowing supersonically
Answer: D
91. The Hazen – Williams formula for head loss due to friction is based upon:
A. rigorous mathematical derivation
B. empirical data
C. semi – empirical analysis
D. screndipity
Answer: B
92. The extended Bernoulli equation includes all of the following terms except:
A. potential energy
B. kinetic energy
C. nuclear energy
D. friction losses
Answer: C
93. An equipotential line is one that:
A. has no velocity component tangent to it
B. has uniformly varying dynamic pressure
C. has no velocity component normal to it
D. exists in case of rotational flow
Answer: A
94. What is the use of a hydraulic jump?
A. increase the flow rate
B. reduce the flow rate
C. reduce the velocity of flow
D. reduce the energy of flow
Answer: D
95. What do you call the lowest portion to storage basin from where the water is not drawn?
A. bottom storage
B. sub soil storage
C. spring reserve
D. dead storage
Answer: D
96. The presence of friction in the hydraulic grade line will always cause the line to slope:
A. down in the direction of the flow
B. upward in the direction of the flow
C. level (no slope)
D. there is no effect of friction on thee energy grade line
Answer: A
97. The presence of a minor loss in the energy grade line will cause the line to slope:
A. down in the direction of the flow
B. upward in the direction of the flow
C. vertically downward
D. there is no effect of friction on the energy grade line
Answer: A
98. What do you call the pressure which the fluid exerts on an immersed object or container
wall?
A. Normal pressure
B. Standard liquid pressure
C. Hydrostatic pressure
D. Gage pressure
Answer: C
99. Viscosity for a fluid is defined as the constant of proportionality between shear stress and
what other variable?
A. The spatial derivative of velocity
B. The time derivative of pressure
C. The time derivative of density
D. The spatial derivative of density
Answer: A
100. What is the classification of the fluid flow if the fluid travels parallel to the adjacent layers
and the paths of the individual particles do not cross each other?
A. Steady flow
B. Laminar flow
C. Uniform flow
D. Turbulent flow
Answer: B
101. Which of the following refers to the measure of a fluid‟s sensitivity to changes in
temperature?
A. Viscosity index
B. Coefficient of viscosity
C. Viscosity ratio
D. Viscosity factor
Answer: A
102. If the number is greater than 1 but lesser than 5, what is the standard classification of the
travel?
A. Transonic travel
B. Subsonic travel
C. Hypersonic travel
D. Supersonic travel
Answer: D
103. What is measure by a Pitot tube?
A. Volumetric discharge
B. Mass flow
C. pressure
D. Velocity
Answer: D
104. What is the difference between the energy grade line and the hydraulic grade line?
A. potential energy
B. pressure energy
C. kinetic energy
D. friction losses
Answer: C
105. Kinetic energy is not neglected in calculations of:
A. high speed flow
B. low speed flow
C. steady flow
D. equilibrium flow
Answer: A
106. Discharge losses through orifice are due to:
A. friction losses
B. minor losses
C. both friction and minor losses
D. pressure losses
Answer: C
107. Which of the following is considered as an important parameter in the study of
compressible flow?
A. speed of fluid
B. speed of sound
C. speed of light
D. speed of fluid flow
Answer: B
108. Is the velocity at which an infinitesimal small pressure wave travels through a medium.
A. Subsonic velocity
B. Hypersonic velocity
C. Sonic velocity
D. Monatomic velocity
Answer: C
109. It is the ratio of actual velocity of the fluid to the velocity of sound.
A. Mach number
B. Froude number
C. Sonic number
D. Euler number
Answer: A
110. The flow is called sonic when Mach number is:
A. equal to 1
B. less than 1
C. more than 1
D. none of these
Answer: A
111. The following flow is sub – sonic when Mach number is:
A. greater than 1
B. less than 1
C. more than 1
D. none of these
Answer: B
112. The flow supersonic when Mach number is:
A. greater than zero
B. less than 1
C. greater than 1
D. none of these
Answer: C
113. The flow is transonic when:
A. M = 0
B. M<1
C. M>1
D. M = 1
114. The pressure decreases as the temperature and velocity increases while the fluid velocity
and Mach number:
A. increases
B. decreases
C. remains constant
D. none of these
Answer: A
115. The Mach number is unity or one at the location of smallest flow area, called the:
A. decreasing area
B. throat
C. increasing area
D. none of these
Answer: B
116. What happens to the velocity of fluid after passing the throat although the flow area
A. increases rapidly
B. decreases rapidly
C. remains constant
D. none of these
Answer: A
117. Which of the following is an example a Newtonian fluid?
A. Motor oils
B. Gas
C. Paints
D. Clay slurries
Answer: B
118. What is the critical pressure of water?
A. 150 kg/cm3
B. less than 200 kg/cm2
C. more than 200 kg/cm2
D. 100 kg/cm2
Answer: C
PAST ME BOARD QUESTIONS
119. The volumetric change of the fluid caused by a resistance is called:
A. volumetric change
B. volumetric index
C. compressibility
D. adhesion
Answer: D
120. The energy of a fluid flowing at any section in pipeline is a function of:
A. velocity of flow only
B. pressure only
C. height above a chosen datum, density, internal energy, pressure and velocity of flow D.
pressure, height above a chosen datum, velocity of flow, density of fluid
Answer: C
121. If the fluid travel parallel to the adjacent layers and the paths of individual particles do not
cross, the fluid is said to be:
A. turbulent
B. critical
C. dynamic
D. laminar
Answer: D
122. Center of pressure on an inclined plane lies:
A. at the centroid
B. above the centroid
C. below the centroid
D. at the metacenter
Answer: C
123. At any instant, if the number of particles passing every cross – section of the stream is the
same, the flow is said to be:
A. steady flow
B. uniform flow
C. continuous flow
D. laminar flow
Answer: A
124. The ratio of cross-sectional area of flow to the wetted perimeter is:
A. hydraulic lead
B. hydraulic section
C. hydraulic mean depth
D. hydraulic gradient
Answer: C
125. If A is the cross-sectional area of the flow and Pw is the wetted perimeter of a pipe, then
what is the hydraulic depth. Hd?
A. Pw – A
B. Pw/A
C. A/Pw
D. Pw x A
Answer: C
126. If Q is the volume in gallon; D is height or elevation in ft, and m is weight in lbs per gallon,
what is the desired energy to lift the water from lower to higher elevation?
A. E = mD/Q
B. E = mDQ
C. E = mQ/D
D. E = QD/m
Answer: B
127. The flow of the convergent section of a nozzle is always subsonic. If the flow subsonic then
the Mach number is:
A. greater than unity
B. less than unity
C. near unity
D. unity
Answer: B
