Top Hydraulics & Fluid Machines Objective Questions Part – 2
1.Buoyant force is
resultant force acting on a floating body
equal to the volume of liquid dis�placed
force necessary to keep a body in equi�librium
the resultant force on a body due to the fluid surrounding it
none of the above.
ANSWER : : the resultant force on a body due to the fluid surrounding it
2.Metacentre is the point of intersection of
vertical upward force through e.g. of body and centre line of body
buoyant force and the centre line of body
mid point between e.g. and centre of buoyancy
all of the above
none of the above.
ANSWER : : buoyant force and the centre line of body
3.Ratio of inertia force to surface Jension is known as
Mach number
Froude number
Reynold’s number
Weber’s number
none of the above.
ANSWER : : Weber’s number
4.Resultant pressure of the liquid in the case of an immersed body acts through
centre of gravity
centre of pressure
metacentre
centre of buoyancy
in between e.g. and centre of pressure.
ANSWER : : centre of pressure
5.An open vessel of water is accelerated up an inclined plane. The free water surface will
be horizontal
make an angle in direction of inclina�tion of inclined plane
make an angle in opposite direction to inclination of inclined plane
any one of above is possible
none of the above.
ANSWER : : make an angle in opposite direction to inclination of inclined plane
6.When a body floating in a liquid, is displaced slightly, it oscillates about
e.g. of body
centre of pressure
centre of buoyancy
metacentre
liquid surface.
ANSWER : : metacentre
7.The two important forces for a floating body are
buoyancy, gravity
buoyancy, pressure
buoyancy, inertial
inertial, gravity
gravity, pressure.
ANSWER : : buoyancy, gravity
8.A model of a reservior is drained in 4 mts by opening the sluice gate. The model scale is 1: 225. How long should it take to empty the prototype ?
900 minutes
4 minutes
4 x (225)3/2 minutes
4 (225)1/3 minutes
4 x V225 minutes.
ANSWER : : 4 x V225 minutes.
9.Centre of pressure on an inclined plane is
at the centroid
above the centroid
below the centroid
at metacentre
at centre of pressure.
ANSWER : : below the centroid
10.If the atmospheric pressure on the surface of an oil tank (sp. gr. 0. is 0.2 kg/cm”, the pressure at a depth of 50 m below the oil surface will be
2 metres of water column
3 metres of water column
5 metres of water column
6 metres of water Column
7 metres of water column.
ANSWER : : 6 metres of water Column
11.Ratio of inertia force to elastic force is known as
Mach number
Froude number
Reynold’s number
Weber’s number
none of the above.
ANSWER : : Mach number
12.According to the principle of buoyancy a body totally or partially immersed in a fluid will be lifted up by a force equal to
the weight of the body
more than the weight of the body
less than the weight of the body
weight of the fluid displaced by the body
weight of body plus the weight of the fluid displaced hy the body.
ANSWER : : weight of the fluid displaced by the body
13.The centre of gravity of the volume of the liquid displaced by an immersed body is called
centre of gravity
centre of pressure
metacentre
centre of buoyancy
centroid.
ANSWER : : centre of buoyancy
14.For a floating body to be in stable equilibrium, its metacentre should be
below the centre of gravity
below the centre of buoyancy
above the centre of buoyancy
between e.g. and centre of pressure
above the centre of gravity.
ANSWER : : above the centre of gravity.
15.For a body floating in a liquid the normal pressure exerted by the liquid acts at
bottom surface of the body
e.g. of the body
metacentre
all points on the surface of the body
all of the above.
ANSWER : : all points on the surface of the body
16.A square surface 3 m x 3 m lies in a vertical line in water pipe its upper edge at vater surface. The hydrostatic force on square surface is
9,000 kg
13,500 kg
1000 kg
27,000 kg
30,000 kg.
ANSWER : : 13,500 kg
17.Choose the wrong statement
The horizontal component of the hydro-static force on any surface is equal to the normal force on the verti�cal projection of the surface
The horizontal component acts through the centre of pressure for the vertical projection
The vertical component of the hydros-tatic force on any surface is equal to the weight of the volume of the liquid above the area
he vertical component passes through the centre of pressure of the volume
Centre of pressure acts at a greater depth than centre of gravity.
ANSWER : : he vertical component passes through the centre of pressure of the volume
18.The line of action of the buoyant force acts through the centroid of the
submerged body
volume of the floating body
volume of the fluid vertically above the body
displaced volume of the fluid
none of the above.
ANSWER : : displaced volume of the fluid
19.Choose the wrong statement
The centre of buoyancy is located at the centre of gravity of the displaced liquid
For stability of a submerged body, the centre of gravity of body must lie directly below the centre of buoyancy
If e.g. and centre of buoyancy coin�cide, the submerged body must lie at neutral equilibrium for all positions
For stability of floating cylinders or spheres, the e.g. of body must lie below the centre of buoyancy
All floating bodies are stable.
ANSWER : : All floating bodies are stable.
20.The df pth of the centre of pressure on a vertical rectangular gate m wide and 6 m high, when the water surface coincides with the top of the gate, is
2.4 m
3.0 m
4.0 m
“2.5 m
5.0 m.
ANSWER : : 3.0 m
21.A ship whose hull length is 100 m is to travel at 10 m/sec. For dynamic similarity, at what velocity should a 1:25 model be towed through water ?
10 m/sec
25 m/sec
2 m/sec
50 m/sec
250 m/sec.
ANSWER : : 2 m/sec
22.Hot wire anemometer is used to measure
pressure in gases
liquid discharge
pressure in liquids
gas velocities
temperature.
ANSWER : : gas velocities
23.The flow in which conditions do not change with time at any point, is known as
one dimensional flow
uniform flow
steady flow
turbulent flow
streamline flow.
ANSWER : : steady flow
Explanation :
24.Flow of water in a pipe about 3 metres in diameter can be measured by
orifice plate
venturi
rotameter
pitot tube
nozzle
ANSWER : : pitot tube
25.The flow in which the velocity vector is identical in magnitude and direction at every point, for any given instant, is known as
one dimensional flow
uniform f^w
steady flow
turbulent flow
streamline flow.
ANSWER : : uniform f^w
26.During the opening of a valve in a pipe line, the flow is
steady
unsteady
uniform
laminar
free vortex type.
ANSWER : : unsteady
27.Non uniform flow occurs when
the direction and magnitude of the velocity at all points are identical
the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time
the magnitude aricf direction of the velocity do not change from point to point in the fluid
the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane
velocity, depth, pressure, etc. change from point to point in the fluid flow.
ANSWER : : velocity, depth, pressure, etc. change from point to point in the fluid flow.
28.Select the correct statement
Local atmospheric pressure depends upon elevation of locality only
Standard atmospheric pressure is the mean local atmospheric pressure a* sea level
Local atmospheric pressure is always below standard atmospheric pressure
A barometer reads the difference be-tween local and standard atmospheric pressure
Gauge piessure is equal to atmos�pheric pressure plus instrument read�ing.
ANSWER : : Standard atmospheric pressure is the mean local atmospheric pressure a* sea level
29.Steady flow occurs when
the direction and magnitude of the velocity at all points are identical
the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time
the magnitude and direction of the velocity do not change from point to point in the fluid
the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane
velocity, depth, pressure, etc. change from point to point in the fluid flow.
ANSWER : : the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time
30.Gradually varied flow is
steady uniform
non-steady non-uniform
non-steady uniform
steady non-uniform
true one-dimensional.
ANSWER : : steady non-uniform
31.True one-dimensional flow occurs when
the direction and magnitude of the veiocity at all points are identical
the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time
the magnitude and direction of the velocity do not change from point to point in the fluid
the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane
velocity, depth, pressure etc. change from point to point in the fluid flow.
ANSWER : : the direction and magnitude of the veiocity at all points are identical
32.The pressure in the air space above an oil (sp. gr. 0. surface in a tank is 0.1 kg/cm”. The pressure at 2.5 m below the oil surface will be
2 metres of water column
3 metres of water column
3.5 metres of water column
4 m of water column
none of the above.
ANSWER : : 3 metres of water column
33.Rotameter is a device used to measure
absolute pressure
velocity of fluid
flow
rotation
velocity of air.
ANSWER : : flow
34.For measuring flow by a venturimeter, if should be installed in
vertical line
horizontal line
inclined line with flow downward
inclined line with upward flow\
in any direction and in any location.
ANSWER : : in any direction and in any location.
35.In an immersed body, centre of pressure is
at the centre of gravity
above the centre of gravity
below be centre of gravity
could be above or below e.g. depend�ing on density of body and liquid
unpredictable.
ANSWER : : below be centre of gravity
36.Flow occurring in a pipeline when a valve is being opened is
steady
unsteady
laminar
vortex
rotational.
ANSWER : : unsteady
37.Total pressure on a lmxlm gate immersed vertically at a depth of 2 m below the free water surface will be
1000 kg
4000 kg
2000 kg
00 kg
16000 kg.
ANSWER : : 1000 kg
38.Uniform flow occurs when
the flow is steady
the flow is streamline
size and shape of the cross section in a particular length remain constant
size and cross section change uniform�ly along length
flow occurs at constant fate.
ANSWER : : size and shape of the cross section in a particular length remain constant
39.In the case of steady flow of a fluid, the acceleration of any fluid particle is
constant
variable
zero
zero under limiting conditions
never zero.
ANSWER : : zero
40.An ideal flow of any fluid must satisfy
Pascal law
Newton’s law of viscosity
boundary layer theory
continuity equation
Bernoulli’s theorem.
ANSWER : : continuity equation
41.The flow in which the particles of a fluid attain such velocities that vary from point to point in magnitude and direction as well as from instant to instant, is known as
one dimensional flow
uniform flow
steady flow
turbulent flow
streamline flow.
ANSWER : : turbulent flow
42.The flow in which each liquid particle has a definite path and their paths do not cross each other is called
one dimensional flow
uniform flow
steady flow
turbulent flow
streamline flow.
ANSWER : : streamline flow.
43.The normal stress is same in all directions at a point in a fluid
only when the fluid is frictionless
only when the fluid is incompressible and has zero viscosity
when there is no motion of one fluid layer relative to an adjacent layer
irrespective of the motion of one fluid layer relative to an adjacent layer
in case of an ideal fluid.
ANSWER : : when there is no motion of one fluid layer relative to an adjacent layer
44.A piece of metal of specific gravity 7 floats in mercury of specific gravity 13.6. What fraction of its volume is under mercury ?
0.5
0.4
0.515
0.5
none of the above.
ANSWER : : 0.515
45.For pipes, laminar flow occurs when Roynolds number is
less than 2000
between 2000 and 4000
more than 4000
less than 4000
none of the above.
ANSWER : : less than 2000
46.The upper surface of a weir over which water flows is known is
crest
nappe
sill
weir top
contracta.
ANSWER : : sill
47.According to Bernoulli’s equation for steady ideal fluid flow
principle of conservation of mass holds
velocity and pressure are inversely proportional
total energy is constant throughout
the energy is constant along a stream-line but may vary across streamlines
none of the above.
ANSWER : : the energy is constant along a stream-line but may vary across streamlines
48.The equation of continuity holds good when the flow
is steady
is one dimensional
velocity is uniform at all the cross sec-tions
all of the above
none of the above.
ANSWER : : all of the above
49.Mach number is significant in
supersonics, as with projectiles and jet propulsion
full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
simultaneous motion through two fluids where there is a surface of dis-continuity, gravity force, and wave making effects, as with ship’s hulls
all of fhe above
none of the above.
ANSWER : : supersonics, as with projectiles and jet propulsion
50.The fluid forces considered in the Navier Stokes equation are
gravity, pressure and viscous
gravity, pressure and turbulent
pressure, viscous and turbulent
gravity, viscous and turbulent
none of the above.
ANSWER : : gravity, pressure and viscous
51.For hypersonic flow, the Mach number is
unity
greater than unity
greater than 2
greater than 4
greater than 10.
ANSWER : : greater than 4
52.A piece of wood having weight 5 kg floats in water with 60% of its volume under the liquid. The specific gravity of wood is
0.
0.6
0.4
0.3
none of the above.
ANSWER : : 0.6
53.Froude number is significant in
supersonics, as with projectile and jet propulsion
full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
simultaneous motion through two fluids where there is a surface of dis-continuity, gravity forces, and wave making effect, as with ship’s hulls
all of the above
none of the above
ANSWER : : simultaneous motion through two fluids where there is a surface of dis-continuity, gravity forces, and wave making effect, as with ship’s hulls
54.A large Roynold number is indication of
smooth and streamline flow
laminar flow
steady flow
turbulent flow
highly turbulent flow.
ANSWER : : highly turbulent flow.
55.Reynolds number is significant in
supersonics, as with projectile and jet propulsion
full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
simultaneous motion through two fluids where there is a surface of dis-continuity, gravity forces, and wave making effect, as with ship’s hulls
all of the above
none of the above.
ANSWER : : full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
56.In a free vortex motion, the radial component of velocity everywhere is
maximum
minimum
zero
non-zero and finite
unpredictable.
ANSWER : : zero
57.Two dimensional flow occurs when
the direction and magnitude of the velocity at all points are identical
the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time
the magnitude and direction of the velocity do not change from point to point in the fluid
the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane
velocity, depth, pressure, etc. change from point to point in the fluid flow.
ANSWER : : the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane
58.Pitot tube is used for measurement of
pressure
flow
velocity
dsscharge
viscosity.
ANSWER : : velocity
59.Uniform flow occurs when
the direction and magnitude of the velocity at all points are identical
the velocity of successive fluid pai-ticles, at any point, is the same at suc�cessive periods of time
the magnitude and direction of the velocity do not change from point to point in the fluid
the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plsr.e
velocity, depth, pressure, etc. change from point to point in the fluid flow.
ANSWER : : the magnitude and direction of the velocity do not change from point to point in the fluid
60.In a forced vortex, the velocity of flow everywhere within the fluid is
maximum
minimum
zero
non-zero finite
unpredictable.
ANSWER : : non-zero finite
61.All the terms of energy in Bernoulli’s equation have dimension of
energy
work
mass
length
time.
ANSWER : : length
62A streamline is defined as the line
parallel to central axis flow
parallel to outer surface of pipe
of equal yelocity in a flow
along which the pressure drop is uniform
which occurs in all flows.
ANSWER : : of equal yelocity in a flow
63.The region between the separation streamline and the boundary surface of the solid body is known as
wake
drag
lift
boundary layer
aerofoil section.
ANSWER : : wake
64.The total energy of each particle at various places in the case of perfect incompres sible fluid flowing in continuous sream
keeps on increasing
keeps on decreasing
remains constant
may increase/decrease
unpredictable.
ANSWER : : remains constant
65.Normal depth in open channel flow is the depth of flow corresponding to
steady flow
unsteady flow
laminar flow
uniform flow
critical flow.
ANSWER : : uniform flow
66.The pressure in Pascals at a depth of 1 m below the free surface of a body of water will be equal to
1 Pa
91Pa
9 Pa
90 Pa
9100 Pa.
ANSWER : : 90 Pa
67.A hydraulic press has a ram of 15 cm diameter and plunger of 1.5 cm. It is required to lift a weight of 1 tonne. The force required on plunger is equal tc
10 kg
100 kg
1000 kg
1 kg
10,000 kg.
ANSWER : : 10 kg
68.At the centre line of a pipe flowing under pressure where the velocity gradient is zero, the shear stress will be
minimum
maximum
zero
negative value
could be any value.
ANSWER : : could be any value.
69.Cavitation will begin when
the pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid
pressure becomes more than critical pressure
flow is increased
pressure is increased
none of the above.
ANSWER : : the pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid
70.Bernoulli equation deals with the law of conservation of
mass
momentum
energy
work
force.
ANSWER : : energy
71Principle of similitude forms the basis of
comparing two identical equipments
designing models so that the result can be converted to prototypes
comparing similarity between design and actual equipment
hydraulic designs
performing acceptance tests.
ANSWER : : designing models so that the result can be converted to prototypes
72.Two pipe systems can be said to be equivalent, when the following quantites are same
friction loss and flow
length and diameter
flow and length
friction factor and diameter
velocity and diameter.
ANSWER : : friction loss and flow
73.For pipes, turbulent flow occurs when Reynolds number is
less than 2000
between 2000 and 4000
more than 4000
less than 4000
none of the above.
ANSWER : : more than 4000