# Civil Engineering Important MCQ PDF-Hydraulics And Fluid Mechanics Part 1

1. Fluid
is a substance that
(a) cannot be subjected to shear forces
(b) always expands until it fills any container
(c) has the same shear stress.at a point regardless of its motion
(d) cannot remain at rest under action of any shear force
(e) flows.
Ans: d
2. Fluid
is a substance which offers no resistance to change of
(a) pressure
(b) flow
(c) shape
(d) volume
(e) temperature.
Ans: c
3.
Practical fluids
(a) are viscous
(b) possess surface tension
(c) are compressible
(d) possess all the above properties
(e) possess none of the above properties.
Ans: d
4. In a
static fluid
(a) resistance to shear stress is small
(b) fluid pressure is zero
(c) linear deformation is small
(d) only normal stresses can exist
(e) viscosity is nil.
Ans: d
5. A fluid
is said to be ideal, if it is
(a) incompressible
(b) inviscous
(c) viscous and incompressible
(d) inviscous and compressible
(e) inviscous and incompressible.
Ans: e
6. An
ideal flow of any fluid must fulfill the following
(a) Newton’s law of motion
(b) Newton’s law of viscosity
(c) Pascal’ law
(d) Continuity equation
(e) Boundary layer theory.
Ans: d
7. If no
resistance is encountered by displacement, such a substance is known as
(a) fluid
(b) water
(c) gas
(d) perfect solid
(e) ideal fluid.
Ans: e
8. The
volumetric change of the fluid caused by a resistance is known as
(a) volumetric strain
(b) volumetric index
(c) compressibility
(e) cohesion.
Ans: c
9. Liquids
(a) cannot be compressed
(b) occupy definite volume
(c) are not affected by change in pressure and temperature
(GO are not viscous
(e) none of the above.
Ans: e
10.
Density of water is maximum at
(a) 0°C
(b) 0°K
(c) 4°C
(d) 100°C
(e) 20°C.
Ans: c
12. The
value of mass density in kgsecVm4 for water at 0°C is
(a) 1
(b) 1000
(c) 100
(d) 101.9
(e) 91
Ans: d
14.
Property of a fluid by which its own molecules are attracted is called
(b) cohesion
(c) viscosity
(d) compressibility
(e) surface tension.
Ans: b
15.
Mercury does not wet glass. This is due to property of liquid known as
(b) cohesion
(c) surface tension
(d) viscosity
(e) compressibility.
Ans: c
16. The
property of a fluid which enables it to resist tensile stress is known as
(a) compressibility
(b) surface tension
(c) cohesion
(e) viscosity.
Ans: c
17.
Property of a fluid by which molecules of different kinds of fluids are attracted
to each other is called
(b) cohesion
(c) viscosity
(d) compressibility
(e) surface tension.
Ans: a
1 The
specific weight of water is 1000 kg/m”
(a) at norma] pressure of 760 mm
(b) at 4°C temperature
(c) at mean sea level
(d) all the above
(e) none of the above.
Ans: d
19.
Specific weight of water in S.I. units is equal to
(a) 1000 N/m3
(b) 10000 N/m3
(c) 9.81 xlO3 N/m3
(d) 9.81 xlO6N/m3
(e) 9.81 N/m3.
Ans: c
20. When
the flow parameters at any given instant remain same at every point, then flow
is said to be
(a) quasi static
(c) laminar
(d) uniform
(e) static.
Ans: d
21. Which
of the following is demensionless
(a) specific weight
(b) specific volume
(c) specific speed
(d) specific gravity
(e) specific viscosity.
Ans: d
22. The
normal stress in a fluid will be constant in all directions at a point only if
(a) it is incompressible
(b) it has uniform viscosity
(c) it has zero viscosity
(d) it is frictionless
(e) it is at rest.
Ans: e
23. 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) inviscous and moving
(e) viscous and moving.
Ans: e
24. An
object having 10 kg mass weighs 9.81kg on a spring balance. The value of ‘g’ at
this place is
(a) 10m/sec2
(b) 9.81 m/sec2
(c) 10.2/m sec
(d) 9.75 m/sec2
(e) 9 m/sec .
Ans: a
25. The
tendency of a liquid surface to contract is due to the following property
(a) cohesion
(c) viscosity
(d) surface tension
(e) elasticity.
Ans: d
26. 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
(e) none of the above.
Ans: a
27. A
perfect gas
(a) has constant viscosity
(b) has zero viscosity
(c) is incompressible
(d) is of theoretical interest
(e) none of the above.
Ans: e
32. For
very great pressures, viscosity of moss gases and liquids
(a) remains same
(b) increases
(c) decreases
(d) shows erratic behaviour
(e) none of the above.
Ans: d
33. A fluid
in equilibrium can’t sustain
(a) tensile stress
(b) compressive stress
(c) shear stress
(d) bending stress
(e) all of the above.
Ans: c
34.
Viscosity of water in comparison to mercury is
(a) higher
(b) lower
(c) same
(d) higher/lower depending on temperature
(e) unpredictable.
Ans: a
35. The
bulk modulus of elasticity with increase in pressure
(a) increases
(b) decreases
(c) remains constant
(d) increases first upto certain limit and then decreases
(e) unpredictable.
Ans: a
36. The
bulk modulus of elasticity
(a) has the dimensions of 1/pressure
(b) increases with pressure
(c) is large when fluid is more compressible
(d) is independent of pressure and viscosity
(e) is directly proportional to flow.
Ans: b
37. A
balloon lifting in air follows the following principle
(a) law of gravitation
(b) Archimedes principle
(c) principle of buoyancy
(d) all of the above
(e) continuity equation.
Ans: d
38. The
value of the coefficient of compressibility for water at ordinary pressure and
temperature in kg/cm is equal to
(a) 1000
(b) 2100
(c) 2700
(d) 10,000
(e) 21,000.
Ans: e
39. The
increase of temperature results in
(a) increase in viscosity of gas
(b) increase in viscosity of liquid
(c) decrease in viscosity of gas
(d) decrease in viscosity of liquid
(e) (a) and (d) above.
Ans: d
40.
Surface tension has the units of
(a) newtons/m
(b) newtons/m
(c) new tons/m
(d) newtons
(e) newton m.
Ans: c
41.
Surface tension
(a) acts in the plane of the interface normal to any line in the surface
(b) is also known as capillarity
(c) is a function of the curvature of the interface
(d) decreases with fall in temperature
(e) has no units.
Ans: a
42. The
stress-strain relation of the newtoneon fluid is
(a) linear
(b) parabolic
(c) hyperbolic
(d) inverse type
(e) none of the above.
Ans: a
43. A
liquid compressed in cylinder has a volume of 0.04 m3 at 50 kg/cm2 and a volume
of 0.039 m3 at 150 kg/cm2. The bulk modulus of elasticity of liquid is
(a) 400 kg/cm2
(b) 4000 kg/cm2
(c) 40 x 105 kg/cm2
(d) 40 x 106 kg/cm2
(e) none of the above.
Ans: b
44. The
units of viscosity are
(a) metres2 per sec
(b) kg sec/metre
(c) newton-sec per metre2
(d) newton-sec per metre
(e) none of the above.
Ans: b
45.
Kinematic viscosity is dependent upon
(a) pressure
(b) distance
(c) level
(d) flow
(e) density.
Ans: e
46. Units
of surface tension are
(a) energy/unit area
(b) distance
(c) both of the above
(d) it has no units
(e) none of the above.
Ans: c
47. Which
of the following meters is not associated with viscosity
(a) Red wood
(b) Say bolt
(c) Engler
(d) Orsat
(e) none of the above.
Ans: d
48. Choose
the correct relationship
(a) specific gravity = gravity x density
(b) dynamicviscosity = kinematicviscosity x density
(c) gravity = specific gravity x density
(d) kinematicviscosity = dynamicviscosity x density
(e) hydrostaticforce = surface tension x gravity.
Ans: b
49.
Dimensions of surface tension are
(a) MlL°T2
(b) MlL°Tx
(c) MlL r2
(d) MlL2T2
(e) MlL°t.
Ans: a
50. For
manometer, a better liquid combination is one having
(a) higher surface tension
(b) lower surface tension
(c) surface tension is no criterion
(d) high density and viscosity
(e) low density and viscosity.
Ans: a
51. If
mercury in a barometer is replaced by water, the height of 3.75 cm of mercury
will be following cm of water
(a) 51 cm
(b) 50 cm
(c) 52 cm
(d) 52.2 cm
(e) 51.7 cm.
Ans: a
52. Choose
the wrong statement.
Alcohol is used in manometer, because
(a) its vapour pressure is low
(b) it provides suitable meniscus for the inclined tube
(c) its density is less
(d) it provides longer length for a given pressure difference
Ans: a
53.
Increase in pressure at the outer edge of a drum of radius R due to rotation at
corad/sec, full of liquid of density p will be
(a) pco2/?2
(b) pco2/?2/2
(c) 2pa2R2
(d) pa2R/2
(e) none of the above.
Ans: b
54. The
property of fluid by virtue of which it offers resistance to shear is called
(a) surface tension
(c) cohesion
(d) viscosity
(e) all of the above.
Ans: d
55. Choose
the wrong statement
(a) fluids are capable of flowing
(b) fluids conform to the shape of the con-taining vessels
(c) when in equilibrium, fluids cannot sustain tangential forces
(d) when in equilibrium, fluids can sustain shear forces
(e) fluids have some degree of compressibility and offer little resistance to
form.
Ans: d
56. The
density of water is 1000 kg/m3 at
(a) 0°C
(b) 0°K
(c) 4°C (d) 20°C
(e) all temperature.
Ans: c
57. If w
is the specific weight of liquid and k the depth of any point from the surface,
then pressure intensity at that point will be
(a) h
(b) wh
(c) w/h
(d) h/w
(e) h/wh.
Ans: b
5 Choose
the wrong statement
(a) Viscosity of a fluid is that property which determines the amount of its
resistance to a shearing force
(b) Viscosity is due primarily to interaction between fluid molecules
(c) Viscosity of liquids decreases with in-crease in temperature
(d) Viscosity of liquids is appreciably affected by change in pressure
(e) Viscosity is expressed as poise, stoke, or saybolt seconds.
Ans: d
59. The
units of kinematic viscosity are
(a) metres2 per sec
(b) kg sec/meter
(c) newton-sec per meter
(d) newton-sec per meter
(e) none of the above.
Ans: a
60. The
ratio of absolute viscosity to mass density is known as
(a) specific viscosity
(b) viscosity index
(c) kinematic viscosity
(d) coefficient of viscosity
(e) coefficient of compressibility.
Ans: c
4-61.
Kinematic viscosity is equal to
(a) dynamic viscosity/density
(b) dynamicviscosity x density
(c) density/dynamic viscosity
(d) 1/dynamicviscosity x density
(e) same as dynamic viscosity.
Ans: a
4.62.
Which of the following is the unit of kinematic viscosity
(a) pascal
(b) poise
(c) stoke
(e) none of the above.
Ans: c
63. A one
dimensional flow is one which
(a) is uniform flow
(c) takes place in straight lines
(d) involves zero transverse component of flow
(e) takes place in one dimension.
Ans: d
64.
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
(e) is provides suitable meniscus.
Ans: d
65. A
pressure of 25 m of head of water is equal to
(a) 25 kN/m2
(b) 245 kN/m2
(c) 2500 kN/m2
(d) 2.5kN/m2
(e) 12.5 kN/m2.
Ans: b
66.
Specific weight of sea water is more that of pure water because it contains
(a) dissolved air
(b) dissolved salt
(c) suspended matter
(d) all of the above
(e) heavy water.
Ans: d
67. If 850
kg liquid occupies volume of one cubic meter, men 0.85 represents its
(a) specific weight
(b) specific mass
(c) specific gravity
(d) specific density
(e) none of the above.
Ans: c
69. Free
surface of a liquid tends to contract to the smallest possible area due to
force of
(a) surface tension
(b) viscosity
(c) friction
(d) cohesion
Ans: a
70. A
bucket of water is hanging from a spring balance. An iron piece is suspended
into water without touching sides of bucket from another support. The spring
(a) increase
(b) decrease
(c) remain same
(d) increase/decrease depending on depth of immersion
(e) unpredictable.
Ans: c
71.
Falling drops of water become spheres due to the property of
(b) cohesion
(c) surface tension
(d) viscosity
(e) compressibility.
Ans: c
72. 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
(e) there is no such criterion.
Ans: b
73. If
cohesion between molecules of a fluid is greater than adhesion between fluid
and glass, then the free level of fluid in a dipped glass tube will be
(a) higher than the surface of liquid
(b) the same as the surface of liquid
(c) lower than the surface of liquid
(d) unpredictable
(e) none of the above.
Ans: c
74. The
point in the immersed body through which the resultant pressure of the liquid
may be taken to act is known as
(a) meta center
(b) center of pressure
(c) center of buoyancy
(d) center of gravity
(e) none of the above.
Ans: b
75. The
total pressure on the surface of a vertical sluice gate 2 m x 1 m with its top
2 m surface being 0.5 m below the water level will be
(a) 500 kg
(b) 1000 kg
(c) 1500 kg
(d) 2000 kg
(e) 4000 kg.
Ans: d
76. 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
(e) Metacentric principle.
Ans: c
77. The
resultant upward pressure of the fluid on an immersed body is called
(a) upthrust
(b) buoyancy
(c) center of pressure
(d) all the above are correct
(e) none of above is correct.
Ans: b
7 The
conditions for the stable equilibrium of a floating body are
(a) the meta-center should lie above the center of gravity
(b) the center of buoyancy and the center of gravity must lie on the same
vertical line
(c) a righting couple should be formed
(d) all the above are correct
(e) none of the above is correct.
Ans: d
79. Poise
is the unit of
(a) surface tension
(b) capillarity
(c) viscosity
(d) shear stress in fluids
(e) buoyancy.
Ans: c
80.
Metacentric height is given as the distance between
(a) the center of gravity of the body andthe meta center
(b) the center of gravity of the body and the center of buoyancy
(c) the center of gravity of the body and the center of pressure
(d) center of buoyancy and metacentre
(e) none of the above.
Ans: a
81. The
buoyancy depends on
(a) mass of liquid displaced
(b) viscosity of the liquid
(c) pressure of the liquid displaced
(d) depth of immersion
(e) none of the above.
Ans: a
82. The
center of gravity of the volume of the liquid displaced by an immersed body is
called
(a) meta-center
(b) center of pressure
(c) center of buoyancy
(d) center of gravity
(e) none of the above.
Ans: c
83. A
piece of metal of specific gravity 13.6 is placed in mercury of specific
gravity 13.6, what fraction of it volume is under mercury?
(a) the metal piece will simply float over the mercury
(b) the metal piece will be immersed in mercury by half
(c) whole of the metal piece will be immersed with its top surface just at
mercury level
(d) metal piece will sink to the bottom
(e) none of the above.
Ans: c
84. The
angle of contact in case of a liquid depends upon
(a) the nature of the liquid and the solid
(b) the material which exists above the free surface of the liquid
(c) both of die above
(d) any one of the above
(e) none of die above.
Ans: c
3.85. Free
surface of a liquid behaves like a sheet and tends to contract to smallest
possible area due to the
(b) force of cohesion
(c) force of friction
(d) force of diffusion
(e) none of die above.
Ans: b
86. Rain
drops are spherical because of
(a) viscosity
(b) air resistance
(c) surface tension forces
(d) atmospheric pressure
(e) none of the above.
Ans: c
87.
Surface energy per unit area of a surface is numerically equal to ..
(a) atmospheric pressure
(b) surface tension
(d) force of cohesion
(e) viscosity.
Ans: b
1-8 The
capillary rise at 20°C in a clean glass tube of 1 mm bore containing water is
ap-proximately
(a) 1 mm
(b) 5 mm
(c) 10 mm
(d) 20 mm
(e) 30 mm.
Ans: e
89. The
difference of pressure between the inside and outside of a liquid drop is
(a)p = Txr
(b)p = T/r
(c) p = T/2r
(d)p = 2T/r
(e) none of the above.
Ans: d
90. 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
(e) none of the above.
Ans: c
91. To
avoid vaporisation in the pipe line, the pipe line over the ridge is laid such
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
(e) none of the above.
Ans: b
92. To
avoid an interruption in the flow of a syphon, an air vessel is provided
(a) at the inlet
(b) at the outlet
(c) at the summit
(d) ay nay point between inlet and outlet
(e) none of the above.
Ans: c
93. The
vapour pressure over the concave surface is
(a) less man the vapour pressure over the plane surface
(b) equal to the vapour pressure over the plane surface
(c) greater than the vapour pressure over the plane surface
(d) zero
(e) none of the above.
Ans: a
94. The
peoperty by virtue of which a liquid opposes relative motion between its
different layers is called
(a) surface tension
(b) co-efficient of viscosity
(c) viscosity
(d) osmosis
(e) cohesion.
Ans: c
95. The
process of diffusion of one liquid into the other through a semi-permeable
membrane is called
(a) viscosity
(b) osmosis
(c) surface tension
(d) cohesion
(e) diffusivity.
Ans: b
96. The
units of dynamic or absolute viscosity are
(a) metres2 per sec
(b) kg sec/meter
(c) newton-sec per meter
(d) newton-sec2 per meter
(e) none of the above.
Ans: c
9 The
continuity equation is connected with
(a) viscous/unviscous fluids
(b) compressibility of fluids
(c) conservation of mass
(e) open channel/pipe flow.
Ans: c
99. The
rise or depression of liquid in a tube due to surface tension wim increase in
size of tube will
(a) increase
(b) remain unaffected
(c) may increase or decrease depending on the characteristics of liquid
(d) decrease
(e) unpredictable.
Ans: d
100.
Liquids transmit pressure equally in all the directions. This is according to
(a) Boyle’s law
(b) Archimedes principle
(c) Pascal’s law
(d) Newton’s formula
(e) Chezy’s equation.
Ans: c