FLUID MECHANICS QUESTION BANK BY BHAGEL SINGH
1 ) Bulk modulus of a fluid is the ratio of
A
shear stress to shear strain
.
B
increase in volume to the viscosity of fluid
.
C
increase in pressure to the volumetric strain
.
D
critical velocity to the viscosity of fluid
.
2) The pressure at a point 4 m below the free surface of water is
A
19.24 kPa
.
B
29.24 kPa
.
C
39.24 kPa
.
D
49.24 kPa
.
3) A structure used to dam up a stream or river over which the water flows is called
A
orifice
.
B
notch
.
C
weir
.
D
Dam
.
4) The coefficient of discharge for an external mouthpiece depends upon
A
velocity of liquid
.
B
pressure of liquid
.
C area of mouthpiece
.
D
length of mouthpiece
.
Answer: Option D
5) The depth of centre of pressure lor an immersed surface inclined at an angle θ with
the liquid surface lies at a distance equal to __________ the centre of gravity.
A
.
below
B
.
above
C
.
below
D
.
above
Answer: Option A
6) A vessel of 4 m3 contains an oil which weighs 30 kN. The specific weight of the oil is
A
4.5 kN/m3
.
B
6 kN/m3
.
C
7.5 kN/m3
.
D
10 kN/m3
.
Answer: Option C
7) Coefficient of discharge Cd is equal to (where Cc = Coefficient of contraction, Cv =
Coefficient of velocity, and Cr = Coefficient of resistance)
A
Cc x Cv
.
B
Cc x Cr
.
C
Cv x Cr
.
D Cc/Cr
.
Answer: Option A
8) The value of coefficient of velocity for a sharp edged orifice __________ with the head of
water.
A
decreases
.
B
increases
.
Answer: Option B
9) An orifice is said to be large, if
A
the size of orifice is large
.
B
the velocity of flow is large
.
C
the available head of liquid is more than 5 times the height of orifice
.
D
the available head of liquid is less than 5 times the height of orifice
.
Answer: Option D
10) The density of a liquid in kg/m3 is numerically equal to its specific gravity.
A
True
.
B
False
.
Answer: Option A
11) The critical depth meter is used to measure
A
velocity of flow in an open channel
.
B
depth of flow in an open channel
.
C
hydraulic jump
.
D
depth of channel
.
Answer: Option C
12) The water pressure per metre length on a vertical masonry wall of dam is (where w =
Specific weight of the liquid, and H = Height of the liquid)
B
wH
.
C
wH2/2
.
D
wH2/4
.
Answer: Option C
13) Froude's number is the ratio of inertia force to
A
pressure force
.
B
elastic force
.
C
gravity force
.
D
surface tension force
.
Answer: Option C
14) According to Chezy's formula, the discharge through an open channel is (where A =
Area of flow, C = Chezy's constant, m = Hydraulic mean depth, and i = Uniform slope in
bed)
A
A √m x i
.
B
C √m x i
.
C
AC√ m x i
.
D
mi√ A x C
.
Answer: Option C
15)When a liquid is flowing through a pipe, the velocity of the liquid is
A
maximum at the centre and minimum near the walls
.
B
minimum at the centre and maximum near the walls
.
C
zero at the centre and maximum near the walls
.
D maximum at the centre and zero near the walls
.
Answer: Option A
16) The pressure of fluid due to hammer blow is
A
directly proportional to density of fluid
.
B
inversely proportional to density of fluid
.
C
directly proportional to (density)1/2 of fluid
.
D
inversely proportional to (density)1/2 of fluid
.
Answer: Option C
17 A flow in which each liquid particle has a definite path, and the paths of individual
) particles do not cross each other, is called
A
steady flow
.
B
uniform flow
.
C
streamline flow
.
D
turbulent flow
.
Answer: Option C
18) A body floating in a liquid is said to be in neutral equilibrium, if its metacentre
A
coincides with its centre of gravity
.
B
lies above its centre of gravity
.
C
lies below its centre of gravity
.
D
lies between the centre of buoyancy and centre of gravity
.
Answer: Option A
19) One cubic metre of water weighs
A 100 litres
.
B
250 litres
.
C
500 litres
.
D
1000 litres
.
Answer: Option D
20) Surface tension force is the product of surface tension per unit length and cross-
sectional area of flow.
A
Correct
.
B
Incorrect
.
Answer: Option B
21) An average value of coefficient of velocity is
A
0.62
.
B
0.76
.
C
0.84
.
D
0.97
.
Answer: Option D
22)The shear stress between the two liquid layers is __________ proportional to the
distance between two layers.
A
directly
.
B
indirectly
.
Answer: Option B
23)The mass per unit volume of a liquid at a standard temperature and pressure is called
A
specific weight
.
B
mass density
.
C
specific gravity
.
D
none of these
.
Answer: Option B
24) The centre of pressure acts __________ the centre of gravity of immersed surface.
A
at
.
B
above
.
C
below
.
Answer: Option C
25) A flow through an expanding tube at constant rate is called
A
steady uniform flow
.
B
steady non-uniform flow
.
C
unsteady uniform flow
.
D
unsteady non-uniform flow
.
Answer: Option B
26) When a body is placed over a liquid, it is subjected to gravitational force and upthrust
of the liquid.
A
True
.
B
False
.
Answer: Option A
27) The velocity of flow is same at all points in the cross-section of a channel.
A
True
.
B
False
.
Answer: Option B
28)The length of a liquid stream while flowing over a weir __________ at the ends of the
sill.
A
expands
.
B
does not change
.
C
contracts
.
Answer: Option C
29) Select the wrong statement
A
An equivalent pipe is treated as an ordinary pipe for all calculations
.
B
The length of an equivalent pipe is equal to that of a compound pipe
.
C
The discharge through an equivalent pipe is equal to that of a compound pipe
.
D The diameter of an equivalent pipe is equal to that of a compound pipe
.
30) The velocity through a channel of circular section will be maximum when the depth
of water is __________ the diameter of the circular channel.
A
0.34 times
.
B
0.67 times
.
C
0.81 times
.
D
0.95 times
.
Answer: Option C
. 31) In a footstep bearing, if the radius of the shaft is doubled, then the torque required to
overcome the viscous resistance will be
A
double
.
B
four times
.
C
eight times
.
D
sixteen times
.
Answer: Option D
32) The specific gravity of an oil whose specific weight is 7.85 kN/m3, is
A
0.8
.
B
1
.
C
1.2
.
D
1.6
.
Answer: Option A
33) The body will float if the force of buoyancy is __________ the weight of the liquid
displaced.
A
equal to
.
B
less than
.
C
more than
.
Answer: Option C
34) According to Darcy's formula, the loss of head due to friction in the pipe is (where f =
Darcy's coefficient, l = Length of pipe, v = Velocity of liquid in pipe, and d = Diameter of
pipe)
A
.
B
.
C
.
D
.
Answer: Option D
35) The ratio of specific weight of a liquid to the specific weight of pure water at a standard
temperature is called
A density of liquid
.
B
specific gravity of liquid
.
C
compressibility of liquid
.
D
surface tension of liquid
.
Answer: Option B
36) The velocity of liquid flowing through an orifice varies with the available head of the
liquid.
A
Agree
.
B
Disagree
.
Answer: Option A
37) The force of buoyancy is always __________ the weight of the liquid displaced by the
body.
A
equal to
.
B
less than
.
C
more than
.
Answer: Option A
38) The quantity of a liquid flowing per second through a section of a pipe or a channel is
called discharge and is measured in cumecs (m3/s).
A
True
.
B
False
.
Answer: Option A
39) The purpose of a surge tank is
A
to control the pressure variations due to rapid changes in the pipe line flow
.
B
to eliminate water hammer possibilities
.
C to regulate flow of water to turbines by providing necessary retarding head of water
.
D
all of the above
.
Answer: Option D
40) The divergent portion of a venturimeter is made longer than convergent portion in
order to
A
avoid the tendency of breaking away the stream of liquid
.
B
to minimise frictional losses
.
C
both (a) and (b)
.
D
none of these
.
Answer: Option C
41) In a venturiflume, the flow takes place at
A
atmospheric pressure
.
B
gauge pressure
.
C
absolute pressure
.
D
none of these
.
Answer: Option A
42) The discharge in an open channel corresponding to critical depth is
A
zero
.
B
minimum
.
C
maximum
.
Answer: Option C
43) The pressure of liquid at throat in a venturimeter is __________ than that at inlet.
A
higher
.
B
lower
.
Answer: Option B
44) A fluid whose viscosity changes with the rate of deformation or shear strain is known
as non-newtonian fluid.
A
True
.
B
False
.
Answer: Option A
45) When the flow in an open channel is gradually varied, the flow is said to be
A
steady uniform flow
.
B
steady non-uniform flow
.
C
unsteady uniform flow
.
D
unsteady non-uniform flow
.
Answer: Option B
46) When the Mach number is equal to unity, the flow is called sonic flow.
A
True
.
B
False
.
Answer: Option A
47) The total pressure on the bottom of a closed cylindrical vessel completely filled up
with a liquid is the sum of the total centrifugal pressure and the weight of the liquid in
the vessel.
A
Correct
.
B
Incorrect
.
Answer: Option A
48) The total pressure on the top of a closed cylindrical vessel competely filled up with a
liquid is
A
directly proportional to (radius)2
.
B
inversely proportional to (radius)2
.
C
directly proportional to (radius)4
.
D
inversely proportional to (radius)4
.
49) Poise is the unit of viscosity in C.G.S. system of units.
A
Agree
.
B
Disagree
.
Answer: Option A
50) When the Mach number is more than 6, the flow is called
A
sub-sonic flow
.
B
sonic flow
.
C
super-sonic flow
.
D
hyper-sonic flow
.
Answer: Option D
51) The separation of flow occurs when the hydrodynamic boundary layer thickness is
reduced to zero.
A
Agree
.
B
Disagree
.
Answer: Option A
52) When a body is immersed wholly or partially in a liquid, it is lifted up by a force equal
to the weight of liquid displaced by the body. This statement is called
A
Pascal's law
.
B
Archimede's principle
.
C
principle of floatation
.
D
Bernoulli's theorem
.
Answer: Option B
53)The pressure at a stagnation point is always low.
A
Agree
.
B
Disagree
.
Answer: Option B
54) In two dimensional flow, the flow does not take place in a curve.
A
True
.
.
B
False
.
Answer: Option B
55) The ratio of the inertia force to the __________ is called Euler's number.
A
pressure force
.
B
elastic force
.
C
surface tension force
.
D
viscous force
.
Answer: Option A
56) A nozzle is generally made of
A
cylindrical shape
.
B
convergent shape
.
C
divergent shape
.
D
convergent-divergent shape
.
57) The unit of surface tension is
A
N/m
.
B
N/m2
.
C
N/m3
.
D
N-m
.
Answer: Option A
58) A moving fluid mass may be brought to a static equilibrium position, by aplying an
imaginary inertia force of the same magnitude as that of the accelerating force but in the
opposite direction. This statement is called
A
Pascal's law
.
B
Archimede's principle
.
C
D-Alembert's principle
.
D
none of these
.
Answer: Option C
59) The specific gravity of water is taken as
A
0.001
.
B
0.01
.
C
0.1
.
D
1
.
Answer: Option D
60) A pitot tube is used to measure the
A
velocity of flow at the required point in a pipe
.
B
pressure difference between two points in a pipe
.
C
total pressure of liquid flowing in a pipe
.
D discharge through a pipe
.
Answer: Option A
61)The total head of a liquid particle in motion is equal to
A
pressure head + kinetic head + potential head
.
B
pressure head - (kinetic head + potential head)
.
C
potential head - (pressure head + kinetic head)
.
D
kinetic head - (pressure head + potential head)
.
Answer: Option A
62)The reciprocal of Euler's number is called Newton number.
A
Yes
.
B
No
.
Answer: Option A
63)The property of a liquid which enables it to resist tensile stress is called its surface
tension.
A
Agree
.
B
Disagree
.
Answer: Option A
64)The magnitude of water hammer depends upon the
A
elastic properties of the pipe material
.
B
elastic properties of the liquid flowing through the pipe
.
C
speed at which the valve is closed
.
D
all of the above
.
Answer: Option D
65)The dynamic viscosity of gases __________ with rise in temperature.
A remain unaffected
.
B
increases
.
C
decreases
.
Answer: Option B
66)A flow in which the quantity of liquid flowing per second is constant, is called
__________ flow.
A
steady
.
B
streamline
.
C
turbulent
.
D
unsteady
.
Answer: Option A
67)The coefficient of venturifiume, generally, lies between
A
0.3 to 0.45
.
B
0.50 to 0.75
.
C
0.75 to 0.95
.
D
0.95 to 1.0
.
Answer: Option D
68)Venturimeter is used to
A
measure the velocity of a flowing liquid
.
B
measure the pressure of a flowing liquid
.
C
measure the discharge of liquid flowing in a pipe
.
D
measure the pressure difference of liquid flowing between two points in a pipe line
.
Answer: Option C
69)A flow is called super-sonic if the
A
velocity of flow is very high
.
B
discharge is difficult to measure
.
C
Mach number is between 1and 6
.
D
none of these
.
Answer: Option C
70)The force present in a moving liquid is
A
inertia force
.
B
viscous force
.
C
gravity force
.
D all of these
.
71)According to Bernoulli's equation
A
.
B
.
C
.
D
.
Answer: Option A
72)The ratio of the inertia force to the elastic force is called
A
Reynold's number
.
B
Froude's number
.
C Weber's number
.
D
Mach number
.
Answer: Option D
73)The velocity of the liquid flowing through the divergent portion of a venturimeter
A
remains constant
.
B
increases
.
C
decreases
.
D
depends upon mass of liquid
.
Answer: Option C
74)Bernoulli's equation is applied to
A
venturimeter
.
B
orifice meter
.
C
pitot tube
.
D
all of these
.
. 75)A fluid having no viscosity is known as
A
real fluid
.
B
ideal fluid
.
C
newtonian fluid
.
D
non-newtonian fluid
.
Answer: Option B
. 76) The depth of centre of pressure (h) for a vertically immersed surface from the liquid
surface is given by (where IG= Moment of inertia of the immersed surface about
horizontal axis through its centre of gravity, A = Area of immersed surface, and x = Depth
of centre of gravity of the immersed surface from the liquid surface)
A
B
.
C
.
D
.
Answer: Option D
77)The velocity at which the turbulent flow starts is known as higher critical velocity.
A
Yes
.
B
No
.
Answer: Option A
78)The specific weight is also known as weight density.
A
Correct
.
B
Incorrect
.
Answer: Option A
79)The theoretical velocity of jet at vena contracta is (where H = Head of water at vena
contracta)
A
2gH
.
B
H√2g
.
C
2g√H
.
D
√2gH
.
Answer: Option D
80) According to Newton's law of viscosity, the shear stress on a layer of a fluid is
__________ to the rate of shear strain.
A
equal to
.
B
directly proportional
.
C
inversely proportional
.
Answer: Option B
