Impotant Hydraulic & Fluid Machines Objective Questions
1.Practical fluids
are viscous
possess surface tension
are compressible
possess all the above properties
possess none of the above properties.
ANSWER : : possess all the above properties
2.The tendency of a liquid surface to contract is due to the following property
cohesion
adhesion
viscosity
surface tension
elasticity.
ANSWER : : surface tension
3.An object having 10 kg mass weighs 9.kg on a spring balance. The value of ‘g’ at this place is
10m/sec2
9. m/sec2
10.2/m sec
9.75 m/sec2
9 m/sec .
ANSWER : : 10m/sec2
4.Property of a fluid by which molecules of different kinds of fluids are attracted to each other is called
adhesion
cohesion
viscosity
compressibility
surface tension.
ANSWER : : adhesion
5.Which of the following is demensionless
specific weight
specific volume
specific speed
specific gravity
specific viscosity.
ANSWER : : specific gravity
6.When the flow parameters at any given instant remain same at every point, then flow is said to be
quasi static
steady state
laminar
uniform
static.
ANSWER : : uniform
7.The normal stress in a fluid will be constant in all directions at a point only if
it is incompressible
it has uniform viscosity
it has zero viscosity
it is frictionless
it is at rest.
ANSWER : : it is at rest.
8.A fluid is said to be ideal, if it is
incompressible
inviscous
viscous and incompressible
inviscous and compressible
inviscous and incompressible.
ANSWER : : inviscous and incompressible.
9.Density of water is maximum at
0�C
0�K
4�C
100�C
20�C.
ANSWER : : 4�C
10.Fluid is a substance which offers no resistance to change of
pressure
flow
shape
volume
temperature.
ANSWER : : shape
11.The property of a fluid which enables it to resist tensile stress is known as
compressibility
surface tension
cohesion
adhesion
viscosity.
ANSWER : : cohesion
12.In a static fluid
resistance to shear stress is small
fluid pressure is zero
linear deformation is small
only normal stresses can exist
viscosity is nil.
ANSWER : : only normal stresses can exist
13.Property of a fluid by which its own molecules are attracted is called
adhesion
cohesion
viscosity
compressibility
surface tension.
ANSWER : : cohesion
14.Liquids
cannot be compressed
occupy definite volume
are not affected by change in pressure and temperature
re not viscous
none of the above.
ANSWER : : none of the above.
15.Mercury does not wet glass. This is due to property of liquid known as
adhesion
cohesion
surface tension
viscosity
compressibility.
ANSWER : : surface tension
16.An ideal flow of any fluid must fulfill the following
Newton’s law of motion
Newton’s law of viscosity
Pascal’ law
Continuity equation
Boundary layer theory.
ANSWER : : Continuity equation
17.A perfect gas
has constant viscosity
has zero viscosity
is incompressible
is of theoretical interest
none of the above.
ANSWER : : none of the above.
18.If no resistance is encountered by displacement, such a substance is known as
fluid
water
gas
perfect solid
ideal fluid.
ANSWER : : ideal fluid.
19.The value of mass density in kgsecVm4 for water at 0�C is
1
1000
100
101.9
91
ANSWER : : 101.9
20.The pressure at a point in a fluid will not be same in all the directions when the fluid is
moving
viscous
viscous and static
inviscous and moving
viscous and moving.
ANSWER : : viscous and moving.
21.The surface tension of mercury at normal temperature compared to that of water is
more
less
same
more or less depending on size of glass tube
none of the above.
ANSWER : : more
22.Specific weight of water in S.I. units is equal to
1000 N/m3
10000 N/m3
9. xlO3 N/m3
9. xlO6N/m3
9. N/m3.
ANSWER : : 9. xlO3 N/m3
23.Choose the wrong statement
fluids are capable of flowing
fluids conform to the shape of the con-taining vessels
when in equilibrium, fluids cannot sus-tain tangential forces
when in equilibrium, fluids can sustain shear forces
fluids have some degree of compres-sibility and offer little resistance to form.
ANSWER : : when in equilibrium, fluids can sustain shear forces
24.Dimensions of surface tension are
MlL�T2
MlL�Tx
MlL r2
MlL2T2
MlL�t.
ANSWER : : MlL�T2
25.For manometer, a better liquid combination is one having
higher surface tension
lower surface tension
surface tension is no criterion
high density and viscosity
low density and viscosity.
ANSWER : : higher surface tension
26.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
pco2/?2
pco2/?2/2
2pa2R2
pa2R/2
none of the above.
ANSWER : : pco2/?2/2
27.If mercury in a barometer is replaced by water, the height of 3.75 cm of mercury will be following cm of water
51 cm
50 cm
52 cm
52.2 cm
51.7 cm.
ANSWER : : 51 cm
28.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
400 kg/cm2
4000 kg/cm2
40 x 105 kg/cm2
40 x 106 kg/cm2
none of the above.
ANSWER : : 4000 kg/cm2
29.The property of fluid by virtue of which it offers resistance to shear is called
surface tension
adhesion
cohesion
viscosity
all of the above.
ANSWER : : viscosity
30.Surface tension
acts in the plane of the interface normal to any line in the surface
is also known as capillarity
is a function of the curvature of the interface
decreases with fall in temperature
has no units.
ANSWER : : acts in the plane of the interface normal to any line in the surface
31.The increase of temperature results in
increase in viscosity of gas
increase in viscosity of liquid
decrease in viscosity of gas
decrease in viscosity of liquid
(a) and (d) above.
ANSWER : : decrease in viscosity of liquid
32.The density of water is 1000 kg/m3 at
0�C
0�K
4�C (d) 20�C
all temperature.
opt 5
ANSWER : : 4�C (d) 20�C
33.The bulk modulus of elasticity
has the dimensions of 1/pressure
increases with pressure
is large when fluid is more compres�sible
is independent of pressure and viscosity
is directly proportional to flow.
ANSWER : : increases with pressure
34.Viscosity of water in comparison to mercury is
higher
lower
same
higher/lower depending on temperature
unpredictable.
ANSWER : : higher
35.A fluid in equilibrium can’t sustain
tensile stress
compressive stress
shear stress
bending stress
all of the above.
ANSWER : : shear stress
36.Units of surface tension are
energy/unit area
distance
both of the above
it has no units
none of the above.
ANSWER : : both of the above
37.The stress-strain relation of the newtoneon fluid is
linear
parabolic
hyperbolic
inverse type
none of the above.
ANSWER : : linear
38.Which of the following meters is not associated with viscosity
Red wood
Say bolt
Engler
Orsat
none of the above.
ANSWER : : Orsat
39.Surface tension has the units of
newtons/m
newtons/m
new tons/m
newtons
newton m.
ANSWER : : new tons/m
40.Choose the wrong statement. Alcohol is used in manometer, because
its vapour pressure is low
it provides suitable meniscus for the in-clined tube
its density is less
it provides longer length for a given pressure difference
it provides accurate readings.
ANSWER : : its vapour pressure is low
41.The units of viscosity are
metres2 per sec
kg sec/metre
newton-sec per metre2
newton-sec per metre
none of the above.
ANSWER : : kg sec/metre
42.A balloon lifting in air follows the following principle
law of gravitation
Archimedes principle
principle of buoyancy
all of the above
continuity equation.
ANSWER : : all of the above
43.Kinematic viscosity is dependent upon
pressure
distance
level
flow
density.
ANSWER : : density.
44.The bulk modulus of elasticity with increase in pressure
increases
decreases
remains constant
increases first upto certain limit and then decreases
unpredictable.
ANSWER : : increases
45.Poise is the unit of
surface tension
capillarity
viscosity
shear stress in fluids
buoyancy.
ANSWER : : viscosity
46.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
higher than the surface of liquid
the same as the surface of liquid
lower than the surface of liquid
unpredictable
none of the above.
ANSWER : : lower than the surface of liquid
47 A one dimensional flow is one which
is uniform flow
is steady uniform flow
takes place in straight lines
involves zero transverse component of flow
takes place in one dimension.
ANSWER : : involves zero transverse component of flow
48.The resultant upward pressure of the fluid on an immersed body is called
upthrust
buoyancy
centre of pressure
all the above are correct
none of above is correct.
ANSWER : : buoyancy
48.The units of kinematic viscosity are
metres2 per sec
kg sec/metre
newton-sec per metre
newton-sec per metre
none of the above.
ANSWER : : metres2 per sec
49.Free surface of a liquid tends to contract to the smallest possible area due to force of
surface tension
viscosity
friction
cohesion
adhesion.
ANSWER : : surface tension
50.The ratio of absolute viscosity to mass den-sity is known as
specific viscosity
viscosity index
kinematic viscosity
coefficient of viscosity
coefficient of compressibility.
ANSWER : : kinematic viscosity
51.The point in the immersed body through which the resultant pressure of the liquid may be taken to act is known as
meta centre
centre of pressure
centre of buoyancy
centre of gravity
none of the above.
ANSWER : : centre of pressure
52.Alcohol is used in manometers because
it has low vapour pressure
it is clearly visible
it has low surface tension
it can provide longer column due to low density
is provides suitable meniscus.
ANSWER : : it can provide longer column due to low density
53.Specific weight of sea water is more that of pure water because it contains
dissolved air
dissolved salt
suspended matter
all of the above
heavy water.
ANSWER : : all of the above
54.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
500 kg
1000 kg
1500 kg
2000 kg
4000 kg.
ANSWER : : 2000 kg
55.A pressure of 25 m of head of water is equal to
25 kN/m2
245 kN/m2
2500 kN/m2
2.5kN/m2
12.5 kN/m2.
ANSWER : : 245 kN/m2
56.A liquid would wet the solid, if adhesion forces as compared to cohesion forces are
less
more
equal
less at low temperature and more at high temperature
there is no such criterion.
ANSWER : : more
57.If 0 kg liquid occupies volume of one cubic meter, men 0. represents its
specific weight
specific mass
specific gravity
specific density
none of the above.
ANSWER : : specific gravity
58.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
Buoyancy
Equilibrium of a floating body
Archimedes’ principle
Bernoulli’s theorem
Metacentric principle.
ANSWER : : Archimedes’ principle
59. Which of the following is the unit of kinematic viscosity
pascal
poise
stoke
faraday
none of the above.
ANSWER : : stoke
60.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 balance reading will
increase
decrease
remain same
increase/decrease depending on depth of immersion
unpredictable.
ANSWER : : remain same
61.Falling drops of water become spheres due to the property of
adhesion
cohesion
surface tension
viscosity
compressibility.
ANSWER : : surface tension
62.Operation of McLeod gauge used for low pressure measurement is based on the principle of
gas law
Boyle’s law
Charle’s law
Pascal’s law
McLeod’s law.
ANSWER : : Boyle’s law
63.The vapour pressure over the concave surface is
less man the vapour pressure over the plane surface
equal to the vapour pressure over the plane surface
greater than the vapour pressure over the plane surface
zero
none of the above.
ANSWER : : less man the vapour pressure over the plane surface
64.Capillary action is due to the
surface tension
cohesion of the liquid
adhesion of the liquid molecules and the molecules on the surface of a solid
all of the above
none of the above.
ANSWER : : all of the above
65.Pressure of the order of 10″‘ torr can be measured by
Bourdon tube
Pirani Gauge
micro-manometer
ionisastion gauge
McLeod gauge.
ANSWER : : ionisastion gauge
66.To avoid an interruption in the flow of a syphon, an air vessel is provided
at the inlet
at the outlet
at the summit
ay nay point between inlet and outlet
none of the above.
ANSWER : : at the summit
67.The capillary rise at 20�C in a clean glass tube of 1 mm bore containing water is ap-proximately
1 mm
5 mm
10 mm
20 mm
30 mm.
ANSWER : : 30 mm.
68.. Free surface of a liquid behaves like a sheet and tends to contract to smallest possible area due to the
force of adhesion
force of cohesion
force of friction
force of diffusion
none of die above.
ANSWER : : force of cohesion
69.Mercury is often used in barometer because
it is the best liquid
the height of barometer will be less
its vapour pressure is so low that it may be neglected
both (b) and (c)
it moves easily.
ANSWER : : both (b) and (c)
70.Newton’s law of viscosity is a relationship between
shear stress anctthejiate of angular dis�tortion
shear stress and viscosity
shear stress, velocity and viscosity
pressure, velocity and viscosity
shear stress, pressure and rate of an-gular distortion.
ANSWER : : shear stress anctthejiate of angular dis�tortion
70.The peoperty by virtue of which a liquid opposes relative motion between its different layers is called
surface tension
co-efficient of viscosity
viscosity
osmosis
cohesion.
ANSWER : : viscosity
71.Liquids transmit pressure equally in all the directions. This is according to
Boyle’s law
Archimedes principle
Pascal’s law
Newton’s formula
Chezy’s equation.
ANSWER : : Pascal’s law
72.The rise or depression of liquid in a tube due to surface tension wim increase in size of tube will
increase
remain unaffected
may increase or decrease depending on the characteristics of liquid
decrease
unpredictable.
ANSWER : : decrease
73.An odd shaped body weighing 7.5 kg and occupying 0.01 m3 volume will be completely submerged in a fluid having specific gravity of
1
1.2
0.8
0.75
1.25.
ANSWER : : 0.75
74.The units of dynamic or absolute viscosity are
metres2 per sec
kg sec/metre
newton-sec per metre
newton-sec2 per metre
none of the above.
ANSWER : : newton-sec per metre
75.To avoid vaporisation in the pipe line, the pipe line over the ridge is laid such that it is not more than
2.4 m above the hydraulic gradient
6.4 m above the hydraulic gradient
10.0 m above the hydraulic gradient
5.0 above the hydraulic gradient
none of the above.
ANSWER : : 6.4 m above the hydraulic gradient
76.If the surface of liquid is convex, men
cohesion pressure is negligible
cohesion pressure is decreased
cohesion pressure is increased
there is no cohesion pressure
none of the above.
ANSWER : : cohesion pressure is increased
77.The process of diffusion of one liquid into the other through a semi-permeable membrane is called
viscosity
osmosis
surface tension
cohesion
diffusivity.
ANSWER : : osmosis
78.The atmospheric pressure with rise in altitude decreases
linearly
first slowly and then steeply
first steeply and then gradually
unpredictable
none of the above.
ANSWER : : first slowly and then steeply
79.The resultant of all normal pressures acts
at e.g. of body
at centre of pressure
vertically upwards
at metacentre
vertically downwards.
ANSWER : : vertically upwards
80.In order to increase sensitivity of U-tube manometer, one leg is usually inclined by angle 9. Sensitivity of inclined tube to sensitivity of U-tube is equal to
sin 9
sin 9
casS
cos 9
tan 9.
ANSWER : : sin 9
81.Centre of buoyancy is the
centroid of the displaced volume of fluid
centre of pressure of displaced volume
e.g. of floating ‘body
does not exist
none of the above.
ANSWER : : centroid of the displaced volume of fluid
82.. The resultant upward pressure of the fluid on an immersed body due to its tendency to uplift the sub-merged body is called
upthrust
reaction
buoyancy
metacentre
centre of pressure.
ANSWER : : buoyancy
83.Dynamic viscosity of most of the liquids with rise in temperature
increases
decreases
remains unaffected
unpredictable
none of the above.
ANSWER : : decreases
84.Piezometer is used to measure
pressure in pipe, channels etc.
atmospheric pressure
very low pressures
difference of pressure between two points
flow.
ANSWER : : very low pressures
85.Dynamic viscosity of most of the gases with rise in temperature
increases
decreases
remains unaffected
unpredictable
none of the above.
ANSWER : : increases
86.The line of action of the buoyant force acts through the
centroid of the volume of fluid verti-cally above the body
centre of the volume of floating body
centre of gravity of any submerged body
centriod of the displaced volume of fluid
none of the above.
ANSWER : : centriod of the displaced volume of fluid
87.Which of the following instruments is used to measure flow on the application of Bernoulli’s theorem
Venturimeter
Orifice plate
nozzle
pitot tube
all of the above.
ANSWER : : all of the above.
90.Which of the following instrument can be used for measuring speed of an aeroplane
Venturimeter
Orifice plate
hot wire anemometer
rotameter
pitot tube.
ANSWER : : pitot tube.
91.Working principle of dead weight pressure gauge tester is based on
Pascal’s law
Dalton’s law of partial pressure
Newton’s law of viscosity .
Avogadro’s hypothesis
Second law of thermodynamic.
ANSWER : : Pascal’s law
92.Euler’s dimensionless number relates the following
inertial force and gravity
viscous force and inertial force
viscous force and buoyancy force
pressure force and inertial force
pressure force and viscous force.
ANSWER : : pressure force and inertial force
93.Which of the following instrument can be used for measuring speed of a submarine moving in deep sea
Venturimeter
Orifice plate
hot wire anemometer
rotameter
pitot tube.
ANSWER : : pitot tube.
94.The centre of pressure of a surface subjected to fluid pressure is the point
on the surface at which resultant pres-sure acts
on the surface at which gravitational force acis
at which all hydraulic forces meet
similar to metacentre
where pressure equivalent to hydraulic thrust will act.
ANSWER : : on the surface at which resultant pres-sure acts
95.Buoyant force is
the resultant force acting on a floating body
the resultant force on a body due to the fluid surrounding it
equal to the volume of liquid dis-placed
the force necessary to maintain equi-librium of a submerged body
none of the above.
ANSWER : : the resultant force on a body due to the fluid surrounding it
96.The speed of sound in a ideal gas varies directly as its
pressure
temperature
density
modulus of elasticity
absolute temperature,
ANSWER : : absolute temperature,
97.A metal with specific gravity of o floating in a fluid of same specific gravity a will
sink to bottom
float over fluid
partly immersed
be fully immersed with top surface at fluid surface
none of the above.
ANSWER : : be fully immersed with top surface at fluid surface
98.A body floats in stable equilibrium
when its meatcentric height is zero
when the metancentre is above e.g.
when its e.g. is below it’s centre of buoyancy
metacentre has nothing to do with position of e.g. for determining stability
none of the above.
ANSWER : : when the metancentre is above e.g.
99.Metacentric height is the distance between the metacentre and
water surface
centre of pressure
centre of gravity
centre of buoyancy
none of the above.
ANSWER : : centre of gravity
100.Centre of pressure compared to e.g. is
above it
below it.
at same point
above or below depending on area of body
none of the above.
ANSWER : : below it.