Fluid Mechanics

Question 1

The fluid property, due to which, mercury does not wet the glass is

a. surface tension
b. viscosity
c. cohesion
d. adhesion

Answer 1

a. surface tension

Question 2

Laminar flow of a Newtonion fluid ceases to exist, when the Reynolds number exceeds

a. 4000
b. 2100
c. 1500
d. 3000

Answer 2

b. 2100

Question 3

When the momentum of one fluid is used for moving another fluid, such a device is called a/an

a. jet pump
b. blower
c. acid egg
d. none of these

Answer 3

a. jet pump

Question 4

The normal stress is the same in all directions at a point in a fluid, when the fluid is

a. non-viscous.
b. incompressible.
c. both (a) and (b).
d. having no motion of one fluid layer relative to the other.

Answer 4

d. having no motion of one fluid layer relative to the other.

Question 5

Head developed by a centrifugal pump depends on its

a. speed
b. impeller diameter
c. both (a) and (b)
d. neither (a) nor (b)

Answer 5

c. both (a) and (b)

Question 6

Hydraulic mean depth (Dm) for a circular pipe of diameter ‘D’ flowing full is 0.25 D. For a circular channel, at Dm = 0.3 D, gives the condition for the maximum

a. flow rate
b. mean velocity
c. both ‘a’ & ‘b’
d. neither ‘a’ nor ‘b’

Answer 6

b. mean velocity

Question 7

The head loss in turbulent flow in a pipe varies

a. as velocity
b. as (velocity)2
c. inversely as the square of diameter
d. inversely as the velocity

Answer 7

b. as (velocity)2

Question 8

Most commonly used joint in the underground pipe lines is the

a. sleevejoint
b. coupling
c. flange
d. expansion join

Answer 8

a. sleevejoint

Question 9

Schedule number of a pipe, which is a measure of its wall thickness, is given by

a. 1000 P’/S
b. 100 P’/S
c. 1000 S/P’
d. 10000 P’/S

Answer 9

a. 1000 P’/S

Question 10

The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the

a. discharge.
b. suction.
c. suction minus vapor pressure of the liquid at suction temperature.
d. minus vapor pressure of the liquid at the discharge temperature.

Answer 10

c. suction minus vapor pressure of the liquid at suction temperature.

Question 11

With increasing flow rate, the hydraulic efficiency of a centrifugal pump

a. monotonically decreases.
b. decreases and then increases.
c. remains constant.
d. increases and then decreases.

Answer 11

a. monotonically decreases.

Question 12

The velocity profile for turbulent flow through a closed conduit is

a. logarithmic
b. parabolic
c. hyperbolic
d. linear

Answer 12

a. logarithmic

Question 13

In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of

a. relative roughness.
b. absolute roughness.
c. friction co-efficient for flows at equal Reynold number.
d. all (a), (b) & (c).

Answer 13

c. friction co-efficient for flows at equal Reynold number.

Question 14

Water hammer in a pipeline results from the

a. bursting of pipelines due to closure by a valve.
b. rapid pressure change due to a rapid change in the rate of flow.
c. pressure increase due to closure of a valve resulting in decrease in rate of flow.
d. none of these.

Answer 14

b. rapid pressure change due to a rapid change in the rate of flow.

Question 15

Molten soap mass is transported by a __________ pump.

a. diaphragm
b. reciprocating
c. gear
d. centrifugal

Answer 15

d. centrifugal

Question 16

Which of the following denotes the effect of compressibility in fluid flow ?

a. Weber number
b. Mach number
c. Euler number
d. Reynolds number

Answer 16

b. Mach number

Question 17

Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe.

a. smaller than
b. larger than
c. same as
d. twice

Answer 17

smaller than

Question 18

The terminal velocity of a small sphere settling in a viscous fluid varies as the

a. first power of its dimeter.
b. inverse of the fluid viscosity.
c. inverse square of the diameter.
d. square of the difference in specific weights of solid & fluid.

Answer 18

b. inverse of the fluid viscosity.

Question 19

If the discharge of a centrifugal pump is throttled, then its suction lift

a. increases
b. decreases
c. remains unchanged
d. data insufficient to predict

Answer 19

a. increases

Question 20

Foot valves provided in pumps are __________ valves.

a. relief
b. three/four way
c. pressure reducing
d. directional control

Answer 20

directional control

Question 21

At high Reynolds number

a. inertial forces control and viscous forces are unimportant.
b. viscous forces predominate.
c. inertial forces are unimportant and viscous forces control.
d. none of these.

Answer 21

a. inertial forces control and viscous forces are unimportant.

Question 22

Power loss in an orificemeter is __________ that in a venturimeter.

a. less than
b. same as
c. more than
d. data insufficient, cannot be predicted

Answer 22

c. more than

Question 23

The terminal velocity of a particle moving through a fluid varies as dp^n. What is the value of n’ for Newton’s law regime ?

a. 0.5
b. 1
c. 1.5
d. 3

Answer 23

a. 0.5

Question 24

What is the normal range of exit cone angle of a venturimeter ?

a. 2 to 5
b. 7 to 15
c. 15 to 25
d. >25

Answer 24

b. 7 to 15

Question 25

The dimension of dynamic viscosity is

a. ML-1T-1
b. L2T-1
c. LT-2
d. ML-1T-2

Answer 25

a. ML-1T-1

Question 26

A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke’s law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity

a. same as that of A.
b. one fourth as that of A.
c. twice as that of A.
d. four times as that of A.

Answer 26

b. one fourth as that of A.

Question 27

The pitot static tube does not measure the __________ pressure.

a. static
b. total
c. difference in static & dynamic
d. (a), (b) and (c)

Answer 27

d. (a), (b) and (c)

Question 28

The fluid in which the shearing stress within it is proportional to the velocity gradient across the sheared section, is called a __________ fluid.

a. Bingham
b. Newtonion
c. perfect
d. none of these

Answer 28

b. Newtonion

Question 29

In fluid flow, cavitation is caused, if the

a. fluid velocity decreases to zero.
b. total energy decreases.
c. both (a) and (b).
d. flow pressure approaches its vapor pressure at the prevailing temperature.

Answer 29

d. flow pressure approaches its vapor pressure at the prevailing temperature.

Question 30

The ratio of the depth of flow to the hydraulic radius for the most economical trapezoidal section, in open channel flow is

a. 0.5
b. 1
c. 1.5
d. 2

Answer 30

d. 2

Question 31

The drag co-efficient for a bacterium moving in water at 1 mm/s, will be of the following order of magnitude (assume size of the bacterium to be 1 micron and kinematic viscosity of water to be 10-6m2/s).

a. 24000
b. 24
c. 0.24
d. 0.44

Answer 31

d. 0.44

Question 32

For Laminar flow through a packed bed, the pressure drop is proportional to (Vs is the superficial liquid velocity and Dp is the particle diameter)

a. Vs/Dp2
b. Vs2/Dp2
c. Vs2/Dp3
d. Vs/Dp3

Answer 32

a. Vs/Dp2

Question 33

The maximum delivery pressure of compressors can be upto __________ atmospheres.

a. 10
b. 100
c. 250
d. 1000

Answer 33

d. 1000

Question 34

Dimension of surface tension is(where, F = force, L = length)

a. FL-1
b. F-1 . L
c. F.L-2
d. F-2 . L

Answer 34

a. FL-1

Question 35

Which of the following is not a dimension-less parameter ?

a. Euler number
b. Specific gravity
c. Fanning friction factor
d. None of these

Answer 35

d. None of these

Question 36

Co-efficient of velocity is __________ the coefficient of discharge.

a. less than
b. more than
c. equal to
d. not related to

Answer 36

b. more than

Question 37

All pipes of a particular nominal size have the same

a. inside diameter
b. outside diameter
c. thickness
d. none of these

Answer 37

b. outside diameter

Question 38

For the transfer of solution of thick slurry, the pump used is a __________ pump.

a. reciprocating
b. gear
c. diaphragm
d. centrifugal

Answer 38

c. diaphragm

Question 39

Which of the following is not concerned with the fluid-particle interaction ?

a. Drag co-efficient
b. Froude number
c. Galileo number
d. Weber number

Answer 39

d. Weber number

Question 40

Maximum theoretical suction lift for water at 15°C by a centrifugal pump is 34 ft. The same for water at 90°C will be __________ ft.

a. 40
b. 34
c. 8
d. 37

Answer 40

c. 8

Question 41

Pick out the wrong statement.

a. Momentum transfer in laminar flow results from veclocity gradient.
b. A fluid in equilibrium is not free from shear stress.
c. The viscosity of a non-Newtonion fluid is a function of temperature only.
d. both (b) and (c)

Answer 41

d. both (b) and (c)

Question 42

Pressure drag does not depend upon the

a. roughness of surface of the body.
b. pressure of main flow only.
c.length of the body in flow direction.
d. all (a), (b) and (c)

Answer 42

d. all (a), (b) and (c)

Question 43

Dimension of absolute viscosity is

a. ML-1T-1
b. MLT-1
c. ML-1T
d. MLT

Answer 43

a. ML-1T-1

Question 44

__________ pumps are axial flow pumps.

a. Turbine
b. Propeller
c. Diffuser
d. none of these

Answer 44

b. Propeller

Question 45

Brownian movement is prominent in the particle size range of __________ microns in case of settling of a particle in a fluid.

a. 2 to 3
b. 0.01 to 0.10
c. 200 to 300
d. 100 to 1000

Answer 45

a. 2 to 3

Question 46

For a particle settling in water at its terminal settling velocity, which of the following is true ?

a. Buoyancy = weight + drag
b. Weight = buoyancy + drag
c. Drag = buoyancy + weight
d. Drag = weight

Answer 46

b. Weight = buoyancy + drag

Question 47

A Bingham fluid of viscosity μ = 10 Pa.s and yield stress, τ0 = 10 KPa, is shared between flat parallel plates separated by a distance of 10-3 m. The top plate is moving with a velocity of 1 m/s. The shear stress on the plate is

a. 10 KPa
b. 20 KPa
c. 30 KPa
d. 40 KPa

Answer 47

b. 20 KPa

Question 48

Pick out the correct statement.

a. A forced vortex occurs when fluid rotates as a solid about an axis.
b. In laminar flow, Newton’s law of viscosity does not apply.
c. A free vortex occurs, when fluidrotates as a solid.
d. In turbulent flow, there are neither cross-currents nor eddies.

Answer 48

a. A forced vortex occurs when fluid rotates as a solid about an axis.

Question 49

Shear stress in a fluid flowing in a round pipe

a. varies parabolically across the cross-section.
b. remains constant over the cross-section.
c. is zero at the centre and varies linearly with the radius.
d. is zero at the wall and increases linearly to the centre.

Answer 49

c. is zero at the centre and varies linearly with the radius.

Question 50

The resistance wire used in a hot wire anemometer for conducting electrical current is made of

a. copper
b. tungsten
c. chromium
d. aluminium

Answer 50

b. tungsten

Question 51

Two dimensional stream function

a. relates velocity and pressure.
b. is constant along a stream line.
c. is constant along an equipotential surface.
d. none of these.

Answer 51

b. is constant along a stream line.

Question 52

What causes cavitation in centrifugal pump ?

a. High suction pressure
b. Low barometric pressure
c. Low suction pressure
d. suction velocity

Answer 52

c. Low suction pressure

Question 53

Draining of shallow pits or sump is done by a sump pump, which is a __________ pump.

a. single stage vertical
b. centrifugal
c. plunger
d. diffuser

Answer 53

a. single stage vertical

Question 54

A hydraulic ram acts as a/an __________ pump.

a. centrifugal
b. reciprocating
c. impulse
d. parallel cylinder

Answer 54

c. impulse

Question 55

The ratio of average fluid velocity to the maximum velocity in case of laminar flow of a Newtonion fluid in a circular pipe is

a. 0.5
b. 1
c. 2
d. 0.66

Answer 55

a. 0.5

Question 56

Choose the correct set of dimensions of viscosity that are equivalent (where, F, M, L, T are dimensions for force, mass, length and time respectively).

a. FL-2T, ML-1T-1
b. FLT, ML-1T-1
c. ML-1T-3, F-1L2T
d. F-1L2T-1, MLT-3

Answer 56

a. FL-2T, ML-1T-1

Question 57

The line of action of the buoyant force passes through the centre of gravity of the

a. submerged body.
b. displaced volume of the fluid.
c. of fluid vertically above the body.
d. horizontal projection of the body.

Answer 57

b. displaced volume of the fluid.

Question 58

Pick out the wrong statement.

a. The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonion fluids is D/4L * delta p
b. In the equation, T gc = k (du/dy)^n the value of ‘n’ for pseudoplastic and dilatant fluids are < 1 and >1 respectively.
c. Shear stress for Newtonion fluid is proportional to the rate of shear in the direction perpendicular to motion.
d. With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids.

Answer 58

d. With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids.

Question 59

The friction factor for turbulent flow in a hydraulically smooth pipe

a. depends only on Reynolds number.
b. does not depend on Reynolds number.
c. depends on the roughness.
d. none of these.

Answer 59

a. depends only on Reynolds number.

Question 60

The pressure at a point in a fluid is not the same in all directions, when the fluid is viscous and

a. moving
b. static
c. old
d. hot

Answer 60

a. moving

Question 61

What causes convective acceleration in fluid flow ?

a. Steep slope in flow
b. Unsteady nature of flow
c. Non-uniformity of flow
d. Turbulence in flow

Answer 61

c. Non-uniformity of flow

Question 62

The Stoke’s stream function applies to the

a. irrotational flow only.
b. ideal/non-viscous fluids only.
c. cases of axial symmetry.
d. of these.

Answer 62

c. cases of axial symmetry.

Question 63

Slugging in a fluidised bed can be avoided by using

a. tall narrow vessel.
b. deep bed of solids.
c. shallow beds of solids and proper choice of particle size.
d. very large particles.

Answer 63

c. shallow beds of solids and proper choice of particle size.

Question 64

The ratio of width to depth for the most economical rectangular section in open channel flow is

a. 0.5
b. 1
c. 1.5
d. 2

Answer 64

d. 2

Question 65

The simple pitot tube measures the __________ pressure.

a. static
b. dynamic
c. total
d. of these

Answer 65

c. total

Question 66

Capacity of a hydraulic accumulator is defined in terms of maximum

a. amount of energy stored.
b. flow rate through accumulator.
c. rate of falling of ram.
d. volume available in the cylinder.

Answer 66

a. amount of energy stored.

Question 67

Three piping networks as shown in the figure are placed horizontally. They are made using identical pipe segments and are subjected to the same pressure drop across them. Assuming no pressure losses at junctions, the flow rates across the three networks are related as Q1 : Q2 : Q3.

<insert>

a. 1:√3: 2
b. 1:2:3
c. 1:2:2
d. 1:√2:√2
</insert>

Answer 67

c. 1:2:2

Question 68

With diminishing cross-sectional area in case of subsonic flow in a converging nozzle, the

a. velocity increases
b. pressure decreases
c. both (a) & (b)
d. neither (a) nor (b)

Answer 68

c. both (a) & (b)

Question 69

Boundary layer separation is characterised by one of the conditions given below, where ‘Re’ is the Reynolds number for the flow. Select the appropriate conditions.

a. Re &laquo_space;1, accelerating flow
b. Re&raquo_space; 1, accelerating flow
c. Re &laquo_space;1, decelerating flow
d. Re&raquo_space;1, decelerating flow

Answer 69

d. Re&raquo_space;1, decelerating flow

Question 70

Manometers measure the __________ pressure.

a. vacuum as well as the atmospheric
b. difference in
c. absolute
d. gage

Answer 70

b. difference in

Question 71

Which of the following fluid forces are not considered in the Navier-Stoke’s equation?

a. Gravity forces
b. Viscous forces
c. Pressure forces
d. Turbulent forces

Answer 71

d. Turbulent forces

Question 72

Which of the following may be termed as a variable orifice flowmeter ?

a. Rotameter
b. Pitot tube
c. V-notch
d. All (a), (b) and (c)

Answer 72

a. Rotameter

Question 73

In turbulent flow, a rough pipe has the same friction factor as a smooth pipe

a. in the zone of complete turbulence.
b. when the roughness projections are much smaller than the thickness of the laminar film.
c. everywhere in the transition zone.
d. the friction factor is independent of the Reynold’s number.

Answer 73

b. when the roughness projections are much smaller than the thickness of the laminar film.

Question 74

Air vessel provided in a reciprocating pump

a. smoothens the flow by avoiding pulsations.
b. increases the volumetric efficiency of the pump.
c. saves the pump from the danger of cavitation.
d. none of these.

Answer 74

d. none of these.

Question 75

Bernoulli’s equation is dependent on the

a. first law of thermodynamics.
b. third law of thermodynamics.
c. law of conservation of momentum.
d. none of these.

Answer 75

d. none of these.

Question 76

The capacity of an accumulator is the maximum

a. energy which it can store.
b. discharge which it can deliver.
c. liquid which it can store.
d. none of these.

Answer 76

a. energy which it can store.

Question 77

(PBE Oct 2023) With increase in the temperature, viscosity of a liquid

a. increases
b. decreases
c. remains constant
d. may increase or decrease; depends on the liquid

Answer 77

b. decreases

Question 78

Vena-contracta pressure tapping is at a distance __________ from the position of an orificemeter fitted in a pipe of internal diameter ‘d’

a. d
b. 0.5 d
c. 2d
d. 4d

Answer 78

b. 0.5 d

Question 79

The pump impeller and the turbine runner in a hydraulic torque converter

a. have the same diameter.
b. have different diameters.
c. are directly coupled.
d. none of these.

Answer 79

b. have different diameters.

Question 80

Reciprocating pumps compared to centrifugal pumps

a. deliver liquid at uniform pressure.
b. handle slurries more efficiently.
c. are not subject to air binding.
d. be operated with delivery valve closed.

Answer 80

c. are not subject to air binding.

Question 81

The fluid property which matters for fall-ing rain drops to acquire spherical shape is its

a. pressure
b. height of descend
c. viscosity
d. surface tension

Answer 81

d. surface tension

Question 82

The simple pitot tube does not measure the

a. static pressure.
b. dynamic pressure.
c. velocity at the stagnation point.
d. all (a), (b) and (c).

Answer 82

d. all (a), (b) and (c).

Question 83

Boundary layer separation occurs when the

a. pressure reaches a minimum.
b. cross-section of the channel is reduced.
c. valve is closed in a pipeline.
d. velocity of sound is reached.

Answer 83

b. cross-section of the channel is reduced.

Question 84

The head loss in turbulent flow in a pipe varies

a. directly as the velocity.
b. inversely as the square of the velocity.
c. approximately as the square of the velocity.
d. inversely as the square of the diameter.

Answer 84

c. approximately as the square of the velocity.

Question 85

For flow through an orifice from a reservoir, the actual velocity at the vena con-tracta is given by

a. √2gh
b. C.V. √2gh
c. Cd √2gh
d. Cc √2gh

Answer 85

b. C.V. √2gh

Question 86

The ratio of the hydraulic radius to the diameter of the channel, for maximum mean velocity of flow in a circular channel, in open channel flow is

a. 0.3
b. 0.9
c. 0.03
d. 0.66

Answer 86

a. 0.3

Question 87

For the free settling of a spherical particle through a fluid, the slope of, CD-log NRe , plot is

a. 1
b. -1
c. 0.5
d. -0.5

Answer 87

b. -1

Question 88

A centrifugal pump loses prime after starting. The reason of this trouble may be

a. incomplete priming.
b. too high a suction lift.
c. low available NPSH and air leaks in the suction pipe.
d. all (a), (b), and (c).

Answer 88

d. all (a), (b), and (c).

Question 89

Venturimeter and orificemeter measures the __________ of the fluid.

a. pressure
b. maximum velocity
c. average velocity
d. point velocity

Answer 89

c. average velocity

Question 90

Surge tanks are provided in high pressure water pipelines to

a. store a definte quantity ofwater all the time,
b. reduce the water hammer.
c. facilitate easy dismantling of pipeline for cleaning and maintenance.
d. none of these.

Answer 90

b. reduce the water hammer.

Question 91

Working principle of manometer comprises of balancing a coloumn of liquid against the pressure to be measured. Inclined tube manometer is especially used for the measurement of __________ pressure.

a. small differential
b. atmospheric
c. absolute
d. gage

Answer 91

a. small differential

Question 92

Isotropic turbulence occurs

a. where there is no velocity gradient.
b. at higher temperatures.
c. only in Newtonion fluids.
d. none of these.

Answer 92

a. where there is no velocity gradient.

Question 93

The co-efficient of drag and lift for an incompressible fluid depends on the

a. Reynolds number
b. Froude number
c. Mach number
d. all (a), (b) and (c)

Answer 93

a. Reynolds number

Question 94

Euler’s equation of motion states, that at every point, the

a. fluid momentum is constant.
b. force per unit mass equals acceleration.
c. rate of mass outflow is equal to the rate of mass inflow.
d. none of these.

Answer 94

b. force per unit mass equals acceleration.

Question 95

The Navier-Stokes equation deals with the law of conservation of

a. mass
b. energy
c. both (a) & (b)
d. momentum

Answer 95

d. momentum

Question 96

Hydraulic intensifier is used for increasing the

a. rate of velocity of liquid supply.
b. rate of flow through delivery pipeline of a pump.
c. intensity of pressure of the liquid.
d. momentum rate through delivery pipe.

Answer 96

c. intensity of pressure of the liquid.

Question 97

Which of the following is the ‘Blaussius equation’, relating friction factor to the Reynolds number ?

a. f = 0.079.NRe^-0.25
b. f^-0.5 = 4.07 loge (NRe√f)^-0.6
c. f^-0.5 = -4loge ( (ε/D / 3.70) + ((1.26 / NRe f^0.5))
d. none of these

Answer 97

a. f = 0.079.NRe^-0.25

Question 98

Hydrometer measures the specific gravity of liquids based on the principles of buoyancy. Pycnometer is used to measure the specific gravity of

a. powder & grannular solids
b. liquids
c. melting point semi-solids
d. all ‘a’, ‘b’ & ‘c’

Answer 98

d. all ‘a’, ‘b’ & ‘c’

Question 99

Euler’s equation of motion is a statement expressing

a. conservation of mass.
b. conservation of energy.
c. Newton’s first law of motion.
d. second law of motion.

Answer 99

a. conservation of mass.

Question 100

During ageing of fluid carrying pipes, the

a. pipe becomes smoother with use.
b. friction factor increases linearly with time.
c. absolute roughness decreases with time.
d. absolute roughness increases linearly with time.

Answer 100

d. absolute roughness increases linearly with time.

Question 101

Pick out the wrong statement.

a. The form drag is dependent upon the occurrence of a wake.
b. The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance.
c. An ideal fluid is the one, which has negligible surface tension and obeys the Newton’s law of viscosity.
d. Existence of the boundary layer in fluid flow is because of viscosity of the fluid.

Answer 101

c. An ideal fluid is the one, which has negligible surface tension and obeys the Newton’s law of viscosity.

Question 102

Mass velocity is independent of temperature & pressure, when the flow is

a. unsteady through unchanged cross-section.
b. steady through changing cross-section.
c. steady and the cross-section is unchanged.
d. unsteady and the cross-section is changed.

Answer 102

c. steady and the cross-section is unchanged.

Question 103

Very small pressure difference (< 5 mm water coloumn) can be most conveniently measured by a/an __________ manometer.

a. U-tube water.
b. U-tube mercury.
c. inclined tube mercury.
d. inclined tube water.

Answer 103

d. inclined tube water.

Question 104

For pipe flows, head is proportional to __________ at constant capacity(where, D = pipe diameter).

a. 1/D
b. 1/D2
c. 1/D5
d. D2

Answer 104

c. 1/D5

Question 105

For a given Reynold number as d/D for an orifice increases, Cd will (where, d & D are orifice & pipe diameters respectively).

a. increase
b. decrease
c. remain constant
d. either (a) or (b); depends on other factors

Answer 105

a. increase

Question 106

The energy equation, E + (P/ρ) + (v^2 + 2g) + gZ = constant (E = internal energy/mass), is applicable to

a. perfect gases only.
b. isothermal flow of gases.
c. adiabatic unsteady flow of gases.
d. all compressible fluids.

Answer 106

d. all compressible fluids.

Question 107

What is the ratio of fluid carrying capacity of two pipes having diameters d1 and d2 respectively ?

a. (d1/d2)^0.8
b. (d1/d2)^0.5
c. (d1/d2)
d. (d1/d2)^2

Answer 107

b. (d1/d2)^0.5

Question 108

A differential pressure cell is used for

a. measuring small pressure difference in gases.
b. measuring small pressure difference in liquids.
c. remote recording of pressure difference.
d. measuring the difference of the impact & the static pressure.

Answer 108

c. remote recording of pressure difference.

Question 109

If more than two branches of pipes are to be connected at the same point, then use a/an

a. elbow
b. union
c. tee
d. none of these.

Answer 109

c. tee

Question 110

In case of a centrifugal pump, the ratio of total delivered pressure to pressure developed with the impeller is called the __________ efficiency.

a. manometric
b. mechanical
c. volumetric
d. overall

Answer 110

a. manometric

Question 111

Acceleration head in a reciprocating pump

a. increases the work done during delivery stroke.
b. decreases the work done during suction stroke.
c. does not change the work requirement of the pump.
d. increases the work done during suction stroke.

Answer 111

c. does not change the work requirement of the pump.

Question 112

The ratio of inertial forces to elastic forces is called the __________ number.

a. Reynolds
b. Mach
c. Euler
d. Weber

Answer 112

b. Mach

Question 113

The equivalent diameter for flow through a rectangular duct of width B and height H is

a. HB / 2(H+B)
b. HB / (H+B)
c. 2HB / (H+B)
d. 4HB / (H+B)

Answer 113

c. 2HB / (H+B)

Question 114

Fluid flow at increasing rate through a diverging pipe is an example of __________ flow.

a. steady uniform
b. non-steady uniform
c. steady non-uniform
d. non-steady non-uniform

Answer 114

d. non-steady non-uniform

Question 115

The temperature in isentropic flow

a. does not depend on Mach number.
b. depends on Mach number only.
c. cannot drop and then increase again downstream.
d. none of these.

Answer 115

b. depends on Mach number only.

Question 116

A fluid element has a velocity V = -y2 . xi + 2yx2 . j. The motion at (x, y) = (l/√2, 1) is

a. rotational and incompressible
b. rotational and compressible
c. irrotational and compressible
d. irrotational and incompressible

Answer 116

b. rotational and compressible

Question 117

Check in a centrifugal pump is

a. provided in the discharge line.
b. generally a globe valve.
c. provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running.
d. all (a), (b) and (c).

Answer 117

d. all (a), (b) and (c).

Question 118

Drag force acting on a body does not depend upon the

a. density of the fluid.
b. density of the body.
c. velocity of the body.
d. projected area of the body.

Answer 118

b. density of the body.

Question 119

Centrifugal pump is normally classified on the basis of the

a. rpm.
b. type of casing.
c. impeller blade angle.
d. number of blades in impeller.

Answer 119

b. type of casing.

Question 120

Where does the maximum stress occur in case of laminar flow of incompressible fluid in a closed conduit of diameter ‘d’?

a. At the centre
b. At d/4 from the wall
c. At the wall
d. At d/8 from the wall

Answer 120

c. At the wall

Question 121

In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where, T = absolute temperature )

a. 1/√T
b. 1/T
c. √T
d. T

Answer 121

c. √T

Question 122

Applying a pressure drop across a capillary results in a volumetric flow rate ‘Q’ under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is

a. Q/2
b. Q/4
c. Q/8
d. Q/16

Answer 122

d. Q/16

Question 123

Cd, Cc and Cv are related (for flow through an orifice) as
(where,
Cd = discharge co-efficient
Cc = co-efficient of contraction

 = area of jet at vena-contracta / area of opening

Cv = co-efficient of velocity

 = actual velocity of vena-contracta / theoretical velocity   )

a. Cd = Cc/Cv
b. Cd = Cc.Cv
c. Cd = Cv/cc
d. none of these

Answer 123

b. Cd = Cc.Cv

Question 124

In an incompressible fluid, the density is

a. greatly affected by moderate changes in pressure.
b. greatly affected only by moderate changes in temperature.
c. not affected with moderate change in temperature & pressure.
d. sensible to changes in both temperature & pressure.

Answer 124

c. not affected with moderate change in temperature & pressure.

Question 125

Check valves are used

a. at high pressure.
b. in bends.
c. for controlling water flow.
d. for unidirectional flow.

Answer 125

d. for unidirectional flow.

Question 126

Velocity distribution for flow between two fixed parallel plates

a. varies parabolically across the section.
b. is constant over the entire cross-section.
c. is zero at the plates and increases linearly to the midplane.
d. none of these.

Answer 126

a. varies parabolically across the section.

Question 127

Priming is needed in a __________ pump.

a. reciprocating
b. gear
c. centrifugal
d. diaphragm

Answer 127

c. centrifugal

Question 128

An ideal nozzle design aims at

a. minimising wall friction.
b. suppressing boundary layer separation.
c. both (a) & (b).
d. neither (a) nor (b).

Answer 128

c. both (a) & (b).

Question 129

Which of the fluid forces are not considered in the Reynold’s equation of flow ?

a. Viscous forces
b. Turbulent forces
c. Pressure forces
d. Compressibility forces

Answer 129

d. Compressibility forces

Question 130

For ideally incompressible fluid, the Mach number will be

a. 1.5
b. 1
c. 0
d. 5

Answer 130

b. 1

Question 131

A mono pump is a __________ pump.

a. centrifugal
b. piston
c. positive acting rotary
d. a group of vacuum

Answer 131

c. positive acting rotary

Question 132

Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of __________ flow type.

a. axial
b. radial
c. mixed
d. none of these

Answer 132

a. axial

Question 133

The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are
P. Inlet pressure Q. Compressor rpm
R. Delivery pressure S. Volumetric flow rate at inlet.

a. P, Q and R
b. P and R
c. R and S
d. P, Rand S

Answer 133

a. P, Q and R

Question 134

Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller.

a. radius of
b. speed of
c. fluid velocity leaving
d. none of these

Answer 134

d. none of these

Question 135

An ideal fluid is

a. non-viscous
b. incompressible
c. both (a) & (b)
d. neither (a) & (b)

Answer 135

c. both (a) & (b)

Question 136

Pick out the Hagen-Poiseulle’s equation.

a. Δp/ρ = 4f (L/D) (V^2 / 2gc)
b. Δp = 32 μLV / gc.D^2
c. Δp/L = 150 (1-ε)/ε^3 ρVo^2 / g^2cDp
d. Δp/L = 1.75 (1-ε)/ε^3 ρVo^2 / gcDp

Answer 136

b. Δp = 32 μLV / gc.D^2

Question 137

In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where M = molecular weight of the gas)

a. 1/√M
b. √M
c. 1/M
d. M

Answer 137

a. 1/√M

Question 138

Boundary layer separation is caused by the

a. reduction of pressure to vapour pressure.
b. boundary layer thickness reducing to zero.
c. adverse pressure gradient.
d. reduction of pressure gradient to zero.

Answer 138

c. adverse pressure gradient.

Question 139

With increase in temperature, the vapor pressure of liquids

a. increases
b. increases linearly
c. decreases
d. remains constant

Question 140

A mercury (specific gravity = 13.6) manometer connected across an orificemeter fitted in a pipe shows a manometer reading of 2 cms. If the manometer liquid is changed to carbon tetrachloride (specific gravity = 1.6), then for the same flow rate of water the new manometer reading will be __________ cms.

a. 17
b. 42
c. 84
d. 1.8

Answer 140

a. 17

Question 141

The ratio of wall drag to total drag in the Stoke’s law range is

a. 0.5
b. 1
c. 1/3
d. 2/3

Question 142

Rotary vacuum pumps can reduce the absolute pressure to as low as __________ mm Hg.

a. 1
b. 0.1
c. 0.01
d. 0.001

Answer 142

c. 0.01

Question 143

A pitched-blade turbine draws __________ a straight blade turbine.

a. less power than
b. more power than
c. same power as
d. data insufficient to predict

Answer 143

a. less power than

Question 144

The most suitable flow measuring device for the fluid flow measurement in a very large diameter pipeline is a

a. weir
b. pitot tube
c. Kennison nozzle
d. V-notch

Answer 144

b. pitot tube

Question 145

A centrifugal pump is called a turbine pump, if it is having a

a. turbine type impeller.
b. vaned diffusion casing.
c. rotating vaned volute.
d. none of these.

Answer 145

b. vaned diffusion casing.

Question 146

Remote control valve is a __________ valve.

a. gate
b. butterfly
c. needle
d. globe

Answer 146

b. butterfly

Question 147

Which of the following quantities are computed by using the hydraulic radius for non-circular ducts ?

a. Velocity and relative roughness.
b. Head loss and velocity.
c. Reynold number, relative roughness and head loss.
d. Reynolds number and friction factor.

Answer 147

c. Reynold number, relative roughness and head loss.

Question 148

Centre of pressure in an immersed body is __________ the centre of gravity.

a. above
b. below
c. at
d. either above or below; depends on the liquid density

Answer 148

b. below

Question 149

The centre of pressure is

a. always below the centroid of the area.
b. always above the centroid of the area.
c. a point on the line of action of the resultant force.
d. at the centroid of the submerged area.

Answer 149

c. a point on the line of action of the resultant force.

Question 150

The uniformity of a gas fluidised bed depends upon the __________ of the solid particles.

a. size
b. surface properties
c. both (a) and (b)
d. neither (a) nor (b)

Answer 150

c. both (a) and (b)

Question 151

Pascal law is not applicable for a/an __________ fluid.

a. accelerating frictionless
b. static
c. uniformly moving
d. none of these

Answer 151

d. none of these

Question 152

In a fluidised bed reactor

a. temperature gradients are very high.
b. temperature is more or less uniform.
c. hot spots are formed.
d. segregation of the solids occurs.

Answer 152

b. temperature is more or less uniform.

Question 153

The flow of a liquid through tapering pipe at a constant rate is an example of __________ flow.

a. steady uniform
b. steady non uniform
c. unsteady uniform
d. unsteady non uniform

Answer 153

b. steady non uniform

Question 154

Pick out the correct statement pertaining to transition/ entrance length in fluid flow.

a. The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change downstream, is called the transition length.
b. Transition length for laminar flow of Newtonion fluids in a pipe of diameter ‘d’ is equal to 0.05. D.NRe.
c. Transition length for turbulent flow of Newtonion fluids in a smooth pipe of diameter ‘d’ is equal to 50 D.
d. all (a), (b) and (c).

Answer 154

d. all (a), (b) and (c).

Question 155

A perfect gas

a. does not satisfy PV= nRT.
b. is incompressible and has zero viscosity.
c. has constant specific heat.
d. can’t develop shear stresses.

Answer 155

c. has constant specific heat.

Question 156

In a/an __________ , the flow rate of fluids is obtained by measuring the difference between the impact and the static pressure.

a. rotameter
b. pitot tube
c. venturimeter
d. flow nozzle

Answer 156

b. pitot tube

Question 157

During fluid flow, variation of shear stress(τ) with velocity gradientat (dv/dy) constant pressure temperature is shown below in the figure

<insert photo from fluid mechanics section 4 no. 7>

In the above figure, Binghom plastic is represented by the curve .

a. V
b. II
c. III
d. I

Answer 157

b. II

Question 158

Speed of sound in an ideal gas depends on its

a. temperature
b. pressure
c. specific volume
d. none of these

Answer 158

a. temperature

Question 159

A centrifugal pump designed for handling water (μ = 1 cp) will deliver __________ when pumping a thicker oil (μ = 30 cp).

a. less head & capacity
b. more head
c. more capacity
d. less head & more capacity

Answer 159

a. less head & capacity

Question 160

If ‘x’ is the depth of flow in an open channel of large width, then the hydraulic radius is equal to

a. x
b. x/2
c. x/3
d. 2x/3

Answer 160

a. x

Question 161

In fluid flow, the boundary layer separation can not occur

a. in case of boundaries experiencing form drag.
b. at points of abrupt changes in the flow directions.
c. in laminar flow.
d. none of these.

Answer 161

d. none of these.

Question 162

For a given fluid flow rate, which of the following incurs maximum head loss ?

a. Orifice meter
b. Venturimeter
c. Flow nozzle
d. All of them incur the same head loss

Answer 162

a. Orifice meter

Question 163

Which of the following assumptions enables the Euler’s equation of motion to be integrated ?

a. The fluid is incompressible.
b. The fluid is non-viscous.
c. The continuity equation is satisfied.
d. The flow is rotational and incompressible.

Answer 163

a. The fluid is incompressible.

Question 164

In case of a pipe exit fitted with a nozzle, the

a. conversion of kinetic head to pressure head is facilitated.
b. conversion of pressure head to kinetic head is facilitated.
c. power transmitted through the nozzle is maximum, when the head lost due to friction in the pipe is equal to one third of the total supply head.
d. both (b) and (c)

Answer 164

d. both (b) and (c)

Question 165

A fluid whose apparent viscosity increases with shear rate is termed as the __________ fluid.

a. Newtonion
b. viscous
c. dilatant
d. non-viscous

Answer 165

c. dilatant

Question 166

Which of the following is the most common pump for pumping either raw sewage or sludge ?

a. Electromagnetic pump
b. Centrifugal pump
c. Reciprocating pump
d. Gear pump

Answer 166

c. Reciprocating pump

Question 167

Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter.

a. 5
b. 50
c. 500
d. 1000

Answer 167

b. 50

Question 168

For turbulent flow of an incompressible fluid through a pipe, the flow rate Q is proportional to (Δ P)n, where ΔP is the pressure drop. The value of exponent ‘n’ is

a. 1
b. 0
c. < 1
d. > 1

Answer 168

c. < 1

Question 169

Reciprocating pumps are not able to compete with the centrifugal pump for industrial use, mainly because these pumps have

a. very low speeds.
b. smaller discharge.
c. higher capital &maintenance cost.
d. high vibrations.

Answer 169

c. higher capital &maintenance cost.

Question 170

Which is the correct relationship for a centrifugal pump ? (where, D = Impeller diameter, inches H = Head developed, ft of liquid pumped N = Speed of pump, rpm)

a. D = 1840 H^0.5/N
b. D = 1840 N/H^0.5
c. H = 1840 D^0.5/N
d. D = 1840 H/N

Answer 170

a. D = 1840 H^0.5/N

Question 171

Which of the following pipe bends will incur the largest head loss ?

a. U-bend
b. 30° bend
c. 45° bend
d. 90° bend

Answer 171

a. U-bend

Question 172

Which is the most efficient and best for measuring very small flow rate of gases ?

a. Venturimeter
b. Orifice meter
c. Rotameter
d. Flow nozzle

Answer 172

c. Rotameter

Question 173

When the water is warm, the height to which it can be lifted by a pump

a. decreases due to reduced viscosity.
b. decreases due to reduced vapour pressure.
c. increases due to increased vapour pressure
d. decreases due to increased frictional resistance.

Answer 173

b. decreases due to reduced vapour pressure.

Question 174

Pipes having diameter 14 inches or more are designated by their

a. outside diameter
b. inside diameter
c. schedule number
d. none of these

Answer 174

a. outside diameter

Question 175

Viscosity of water at 40°C lies in the range of

a. 1 x 10^-3 to 2 x 10-^3 kg/m.s
b. 0.5 x 10^-3 to 1 x 10^-3 kg/m.s
c. 1 to 2 kg/m.s
d. 0.5 to 1 kg/m.s

Answer 175

b. 0.5 x 10^-3 to 1 x 10^-3 kg/m.s

Question 176

A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, the new discharge will be __________ litres/minute.

a. 500
b. 200
c. 1000
d. 750

Answer 176

a. 500

Question 177

The dimension of kinematic viscosity is

a. ML-2T-1
b. L2T-1
c. ML-2T-2
d. none of these

Answer 177

b. L2T-1

Question 178

A pipe of I.D. 4 m is bifurcated into two pipes of I.D. 2 m each. If the average velocity of water flowing through the main pipe is 5 m/sec, the average velocity through the bifurcated pipes is

a. 20 m/sec
b. 10 m/sec
c. 5√2 m/sec
d. 5 m/sec

Answer 178

b. 10 m/sec

Question 179

Turbulent flow generally occurs for cases involving

a. highly viscous fluid
b. very narrow passages
c. very slow motion
d. none of these

Answer 179

d. none of these

Question 180

Lower BWG means __________ of the tube.

a. lower thickness
b. lower cross-section
c. outer diameter
d. inner diameter

Answer 180

b. lower cross-section

Question 181

For laminar flow of Newtonion fluid in a circular pipe, the velocity distribution is a function of the distance ‘d’ measured from the centre line of the pipe, and it follows a __________ relationship.

a. logarithmic
b. parabolic
c. hyperbolic
d. linear

Answer 181

b. parabolic

Question 182

The Prandtl mixing length is

a. zero at the pipe wall and is a universal constant.
b. independent of radial distance from the pipe axis.
c. independent of the shear stress.
d. useful for computing laminar flow problems.

Answer 182

d. useful for computing laminar flow problems.

Question 183

N^2Re/NFr is called the __________ number.

a. Brinkman
b. Galileo
c. Archimedes
d. Euler

Answer 183

b. Galileo

Question 184

The location of centre of pressure, which defines the point of application of the total pressure force on the surface, can be calculated by applying the principle of moments according to which “sum of the moment of the resultant force about an axis is equal to the sum of the components about the same axis”. The centre of pressure of a rectangular surface (of width ‘w’) immersed vertically in a static mass of fluid is at a depth of(where, y = depth of the liquid)

a. 1 / y/3
b. 2y/3
c. 1/ y/4
d. 3y/4

Answer 184

b. 2y/3

Question 185

As the velocity V and thus the Reynolds number of a flow past a sphere increases from very low value, the drag force for Re &laquo_space;1

a. increases linearly with V.
b. decreases linearly with V.
c. decreases as V2.
d. none of these.

Answer 185

a. increases linearly with V.

Question 186

Self-priming centrifugal pump can be used for

a. booster service.
b. pumping liquid fertilisers (e.g. liquid NH3).
c. pumping industrial wastes.
d. all (a), (b) and (c).

Answer 186

d. all (a), (b) and (c).

Question 187

Water hammer is caused, when water flowing in a pipe is suddenly brought to rest by closing the valve. The extent of pressure thus produced due to water hammer depends on the

a. pipe length
b. fluid velocity in the pipe
c. time taken to close the valve
d. all (a), (b) and (c)

Answer 187

d. all (a), (b) and (c)

Question 188

Bernoull’s equation does not apply to the functioning of a/an

a. venturimeter
b. orificem
c. pitot tube
d. none of these

Answer 188

d. none of these

Question 189

What is the shear rate at the pipe wall, in case of laminar flow of Newtonion fluids in a pipe of diameter ‘D’ & length ‘L’ incurring a pressure drop ‘Δp’ with average velocity ‘Vavg’?

a. D Δp/8L
b. D Δp/4L
c. 8 . Vavg/D
d. 4 . Vavg/D

Answer 189

c. 8 . Vavg/D

Question 190

Pascal’s law is valid, only when the fluid is

a. frictionless and at rest.
b. at rest.
c. at rest and when the frictionless fluid is in motion.
d. none of these.

Answer 190

b. at rest.

Question 191

A centrifugal pump is used to pump water through a horizontal distance of 150 m, and then raised to an overhead tank 10 m above. The pipe is smooth with an I.D of 50 mm. What head (m of water) must the pump generate at its exit (E) to deliver water at a flow rate of 0.001 m3/s? The Fanning friction factor, f is 0.0062.

<insert photo from fluid mechanics section 4 no. 41>

a. 10 m
b. 11 m
c. 12 m
d. 20 m

Answer 191

b. 11 m

Question 192

The pressure head of a flow meter remains constant for

a. venturimeter
b. orificemeter
c. rotameter
d. pitot tube

Answer 192

c. rotameter

Question 193

A venturimeter can not be used for the direct measurement of

a. datum difference in the stretch of pipeflow
b. pressure difference in the flow throughpipeline.
c. friction loss in pipe flow.
d. all (a), (b) and (c).

Answer 193

d. all (a), (b) and (c).

Question 194

A double acting reciprocating pump compared to a single acting pump (of almost same size working under same pressure levels) would give almost double

a. head
b. discharge
c. efficiency
d. none of these

Answer 194

b. discharge

Question 195

Which of the following is used for very accurate measurement of flow of gas at low velocity ?

a. Pitot tube
b. Rotameter
c. Segmental orificemeter
d. Hot wire annemometer

Answer 195

d. Hot wire annemometer

Question 196

The rate of shear versus the shear stress curves are time dependent for __________ fluid.

a. thixotropic
b. rheopectic
c. both (a) & (b)
d. neither (a) nor (b)

Answer 196

c. both (a) & (b)

Question 197

In Newton’s law range, the drag co-efficient for the motion of spherical particle in a stationary fluid is

a. 0.44
b. 0.044
c. 4.4
d. 44

Answer 197

a. 0.44

Question 198

A pressure of 10 m head of water is equivalent to __________ kN/m2.

a. 98
b. 147
c. 196
d. 49

Answer 198

a. 98

Question 199

A pressure head of 320 metres of water in meters of CCl4 (sp.gr = 1.6) will be

a. 100
b. 200
c. 320
d. 160

Answer 199

b. 200

Question 200

Pick out the Kozney-Karman equation (valid for low NRe) for fluid flow through a packed bed of solids.

a. Δp/ρ = 4f (L/D) (V^2 / 2gc)
b. fp = 150(1-ε) / NRe + 1.75
c. - Δp gc D^2p ε^3 /L ˉvo μ (1-ε)^2 = 150
d. - Δp/δ L gc/v^2o Dp ε^3 / 1-ε = 1.75

Answer 200

c. - Δp gc D^2p ε^3 /L ˉvo μ (1-ε)^2 = 150

Question 201

The ratio of the wall drag to the form drag in the Stoke’s law range (for motion of spherical particles in a stationary fluid) is

a. 0.5
b. 1
c. 2
d. 0.33

Answer 201

c. 2

Question 202

For turbulent flow in smooth circular pipe, the velocity distribution is a function of the distance ‘d’ measured from the wall of the pipe and the friction velocity ‘v’, and it follows a __________ relationship.

a. logarithmic
b. linear
c. hyperbolic
d. parabolic

Answer 202

a. logarithmic

Question 203

Maintenance cost of a __________ pump for a particular duty is the least.

a. centrifugal
b. reciprocating
c. volute
d. gear

Answer 203

a. centrifugal

Question 204

Choking in case of pipe flow means that a

a. specified mass flow rate can not be achieved.
b. valve is closed in the line.
c. restriction in flow
cross-section area occurs.
d. none of these.

Answer 204

a. specified mass flow rate can not be achieved.

Question 205

Velocity of liquid hydrocarbon fuels in a pipeline can not be measured by magnetic flowmeters, because their __________ is very low/small.

a. thermal conductivity
b. electrical conductivity
c. specific gravity
d. electrical resistivity

Answer 205

b. electrical conductivity

Question 206

The nominal size of a hose pipe is specified by its

a. I.D.
b. O.D.
c. thickness
d. none of these

Answer 206

a. I.D.

Question 207

Transition from laminar flow to turbulent flow is aided by the

a. surface roughness and curvature (i.e.sharp corners).
b. vibration.
c. pressure gradient and the compressibility of the flowing medium.
d. all (a), (b) & (c).

Answer 207

d. all (a), (b) & (c).

Question 208

For flow of fluids through packed bed, the superficial velocity is

a. less than the average velocity through channels.
b. more than the average velocity through channels.
c. dependent on the pressure drop across the bed.
d. same as the average velocity through channels.

Answer 208

a. less than the average velocity through channels.

Question 209

Cd is always __________ Cc.

a. greater than
b. less than
c. equal to
d. either more or less than

Answer 209

a. greater than

Question 210

Buoyant force

a. for non-symmetrical bodies is not vertical.
b. depends on the depth of the submergence of the floating body.
c. depends on the weight of the floating body.
d. none of these.

Answer 210

c. depends on the weight of the floating body.

Question 211

Which of the following is an undesirable property of a manometric liquid ?

a. Non-sticky & non-corrosive nature.
b. High vapour pressure.
c. Low viscosity & surface tension.
d. Low co-efficient of thermal expansion.

Answer 211

b. High vapour pressure.

Question 212

Characteristic curves for a centrifugal pump plotted against its capacity is shown in the diagram. x, y and z denote respectively

<insert photo from fluid mechanics section 5 no. 12>

a. efficiency, head and B.H.P.
b. head, efficiency and B.H.P.
c. B.H.P., efficiency and head
d. efficiency, B.H.P. and head

Answer 212

b. head, efficiency and B.H.P.

Question 213

Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head.

a. manometric
b. total
c. static
d. friction

Answer 213

a. manometric

Question 214

The speed of sound in an ideal gas varies as the

a. temperature
b. pressure
c. density
d. none of these

Answer 214

d. none of these

Question 215

The maximum head that can be developed by a single impeller is __________ ft.

a. 25
b. 100
c. 250-300
d. 1000

Answer 215

c. 250-300

Question 216

The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is

a. < 1
b. 1
c. > 1
d. 2

Answer 216

a. < 1

Question 217

The general relationship between speed N, head H, power P and discharge Q for a centrifugal pump is

a. Q∝N : H∝N^2 : P∝N^3
b. Q∝N^2 : H∝N^3 : P∝N
c. Q∝N : H∝N^3 : P∝N^2
d. Q∝N^3 : H∝N : P∝N^2

Answer 217

a. Q∝N : H∝N^2 : P∝N^3

Question 218

What is the ratio of the velocity at the axis of the pipe to the mean velocity of flow in case of pipe flow under viscous condition ?

a. 0.5
b. 0.67
c. 1
d. 2

Answer 218

d. 2

Question 219

Foot valve provided in the pump is a __________ valve.

a. direction control
b. back pressure
c. relief
d. pressure reduction

Answer 219

b. back pressure

Question 220

The discharge co-efficient for an orificemeter does not depend upon the

a. pipe length.
b. ratio of pipe diameter to orifice diameter.
c. type of orifice & the Reynolds number.
d. pipe diameter.

Answer 220

a. pipe length.

Question 221

Which of the following options will facilitate the achievement of a very high head (say 30 metres) in case of a centrifugal pump?

a. Increasing the impeller speed and the volute area.
b. Increasing the number of vanes in the impeller.
c. Mounting of two or more impellers in series on a single shaft.
d. Either of (a), (b) or (c).

Answer 221

c. Mounting of two or more impellers in series on a single shaft.

Question 222

An equipotential line is __________ to the velocity vector at every point.

a. normal
b. abnormal
c. tangential
d. none of these

Answer 222

a. normal

Question 223

Specific speed for a centrifugal pump is

a. N√ Q / H^(3/4)
b. N√ Q / H^(2/3)
c. N^3Q^5 / H^(1/3)
d. N√ Q / H

Answer 223

a. N√ Q / H^(3/4)

Question 224

Path followed by water jet issuing from the bottom of a water tank will be a

a. parabola (vertex being at the opening).
b. hyperbola.
c. horizontal straight line.
d. zig-zag path (which is geometrically undefined).

Answer 224

a. parabola (vertex being at the opening).

Question 225

Which of the following produces maximum pressure difference for transportation of gases ?

a. Vaccum pumps
b. Blowers
c. Fans
d. Compressors

Answer 225

d. Compressors

Question 226

For flow through a venturi at a particular discharge, the correct relationships among velocities at point X, Y and Z would be

a. V1 < V2 < V3
b. V2 > V1 and V2 > V3
c. V1 > V2 > V3
d. none of these.

Answer 226

b. V2 > V1 and V2 > V3

Question 227

Drag co-efficient in hindered settling is __________ that in free settling.

a. less than
b. equal to
c. not necessarily greater than
d. always greater than

Answer 227

d. always greater than

Question 228

Efficiency of power transmission (η) through a circular pipe is given by (ht - hf)/ht, which has a maximum value of __________ percent.

a. 33:3
b. 50
c. 66.6
d. 88.8

Answer 228

c. 66.6

Question 229

One dimensional fluid flow implies the

a. flow in straight lines only.
b. uniform flow.
c. steady uniform flow.
d. flow in which transverse components are zero.

Answer 229

d. flow in which transverse components are zero.

Question 230

__________ forces act on a particle moving through a stationary fluid.

a. Gravity
b. Drag
c. Buoyant
d. all (a), (b), & (c)

Answer 230

d. all (a), (b), & (c)

Question 231

In frictional fluid flow, the quantity, P/ρ + v^2 / 2gc + gz/gc , is

a. constant along a streamline.
b. not constant along a streamline.
c. increased in the direction of flow.
d. none of these.

Answer 231

b. not constant along a streamline.

Question 232

Hydraulic radius is the ratio of

a. wetted perimeter to flow area.
b. flow area to wetted perimeter.
c. flow area to square of wetted perimeter.
d. square root of flow area to wetted perimeter.

Answer 232

b. flow area to wetted perimeter.

Question 233

The unit of bulk modulus of elasticity for a liquid in S.I. unit is

a. N
b. N/m
c. N/m^2
d. N/m^3

Answer 233

c. N/m^2

Question 234

Power requirement of fans having constant wheel diameter varies __________ fan speed.

a. as square of
b. directly as
c. as cube of
d. none of these

Answer 234

c. as cube of

Question 235

In the low Reynolds number region, the drag force on a sphere is proportional to

a. V
b. V^2
c. V^4
d. V^0.5

Answer 235

a. V

Question 236

The continuity equation

a. is independent of the compressibility of the fluid.
b. is dependent upon the viscosity of the fluid.
c. represents the conservation of mass.
d. none of these.

Answer 236

c. represents the conservation of mass.

Question 237

Experimental study of laminar fluid flow through a circular tube was conducted by

a. Reynolds
b. Hagen and Poiseuille
c. Pascal
d. Blake-Plummer

Answer 237

b. Hagen and Poiseuille

Question 238

The most economical flow control valve for use with large diameter pipes is a

a. butterfly valve
b. globe valve
c. needle valve
d. none of these

Answer 238

a. butterfly valve

Question 239

Each term in Bernaulli’s equation represents the __________ of the fluid.

a. energy per unit mass
b. energy per unit weight
c. force per unit mass
d. none of these

Answer 239

b. energy per unit weight

Question 240

Which of the following is a dimensionless parameter ?

a. Angular velocity
b. Specific weight
c. Kinematic viscosity
d. None of these

Answer 240

d. None of these

Question 241

If the head over the triangular notch is doubled, the discharge will increase by __________ times.

a. 2
b. 2.828
c. 5.657
d. 4

Answer 241

c. 5.657

Question 242

Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1. If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe, will

a. increase.
b. decrease.
c. remain unchanged.
d. increase or decrease depending on the pipe material.

Answer 242

a. increase.

Question 243

What is the force required (in Newtons) to hold a spherical balloon stationary in water at a depth of H from the air-water iterface? The balloon is of radius 0.1 m and is filled with air.

a. 4ng/3
b. 0.01ngH/4
c. 0.01ngH/8
d. 0.04ngH/3

Answer 243

a. 4ng/3

Question 244

For the laminar flow of a fluid in a circular pipe of radius R, the Hagen-Poisseule equation predicts the volumetric flow rate to be proportional to

a. R
b. R^2
c. R^4
d. R^0.5

Answer 244

c. R^4

Question 245

Interstage coolers are provided in a multistage compressor to

a. save power in compressing a given volume to a given pressure.
b. cool the delivered air.
c. achieve the exact delivery pressure.
d. none of these.

Answer 245

a. save power in compressing a given volume to a given pressure.

Question 246

Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the __________ decreases.

a. NPSH required.
b. BHP required by the pump.
c. head of the liquid pumped.
d. all (a), (b) and (c).

Answer 246

d. all (a), (b) and (c).

Question 247

Reynolds number is the ratio of

a. viscous forces to gravity forces.
b. inertial forces to viscous forces.
c. viscous forces to inertial forces.
d. inertial forces to gravity forces.

Answer 247

b. inertial forces to viscous forces.

Question 248

For the manometer set up shown in the figure, the pressure difference PA - PB is given by

<insert photo from fluid mechanics section 5 no. 48>

a. (ρH - ρair)gH
b. (ρH - ρL)gH
c. (ρH - ρL) gH + (ρL - ρair) . g(L - H)
d. (ρH - ρL) gL + (ρL - ρair)gH

Answer 248

a. (ρH - ρair)gH

Question 249

The discharge through a venturimeter depends upon

a. pressure drop only.
b. its orientation.
c. co-efficient of contraction only.
d. none of these.

Answer 249

a. pressure drop only.

Question 250

N. second/m^2 is

a. the S.I. unit of dynamic viscosity.
b. the S.I. unit of kinematic viscosity.
c. equivalent to one poise.
d. equivalent to one stoke.

Answer 250

a. the S.I. unit of dynamic viscosity.

Question 251

The distance between metacentre and __________ is called metacentric height.

a. water surface
b. centre of gravity
c. centre of buoyancy
d. none of these

Answer 251

b. centre of gravity

Question 252

Check valve is used for __________ flow.

a. very precise control of
b. unidirectional
c. multidirectional
d. none of these

Answer 252

b. unidirectional

Question 253

Capacity of a rotary gear pump can be varied by

a. changing the speed of rotation.
b. bleeding air into suction.
c. bypassing liquid from the suction or discharge line.
d. all (a), (6) and (c).

Answer 253

d. all (a), (6) and (c).

Question 254

For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor.

a. brings about no further reduction of
b. increases
c. decreases
d. none of these

Answer 254

a. brings about no further reduction of

Question 255

Power number is the ratio of

a. drag stress to inertial stress.
b. inertial stress to drag stress.
c. inertial stress to gravitational stress.
d. gravitational stress to drag stress.

Answer 255

a. drag stress to inertial stress.

Question 256

The momentum correction factor for the velocity distribution of laminar flow is

a. 1.3
b. 1.66
c. 2.5
d. none of these

Answer 256

d. none of these

Question 257

For the same flow rate of a fluid, the pressure drop is the least for

a. venturimeter
b. orificemeter
c. flow-nozzle
d. Δp is same for all

Answer 257

a. venturimeter

Question 258

The valve commonly used in pipes larger than 2” dia is a

a. globe valve
b. plug-cock
c. gate valve
d. check valve

Answer 258

c. gate valve

Question 259

Foot valves are provided in the suction line of a centrifugal pump to

a. avoid priming, every time we start the pump.
b. remove the contaminant present in the liquid.
c. minimise the fluctuation in discharge.
d. control the liquid discharge.

Answer 259

a. avoid priming, every time we start the pump.

Question 260

An ideal fluid is

a. frictionless & incompressible.
b. one, which obeys Newton’s law of viscosity.
c. highly viscous.
d. none of these.

Answer 260

a. frictionless & incompressible.

Question 261

In area meter (e.g., rotameter), with increase in the fluid flow rate, the

a. pressure drop increases linearly.
b. pressure drop is almost constant.
c. area through which fluid flows does not vary.
d. none of these.

Answer 261

b. pressure drop is almost constant.

Question 262

Drag co-officient CD, in Stoke’s law range is given by

a. CD = 16 / Re,ρ
b. CD = 24 / Re,ρ
c. CD = 18.4 / Re,ρ
d. CD = 0.079 / Re^0.25,ρ

Answer 262

b. CD = 24 / Re,ρ

Question 263

In power law, ζ = A * [d/dy (u)] ^ 2 + B , then the fluid is

a. Newtonian
b. dilatant
c. thixotropic
d. rheopectic

Answer 263

a. Newtonian

Question 264

The buoyant force acting on a floating body is dependent on the

a. viscosity of the liquid.
b. weight of the liquid displaced.
c. depth of immersion of the body.
d. surface tension of the liquid.

Answer 264

b. weight of the liquid displaced.

Question 265

A Newtonion fluid is that

a. which follows Newton’s law of motion.
b. which needs a minimum shear, before it starts deforming.
c. for which shear & deformation are related as τ = μ ∂u / ∂y
d. none of these.

Answer 265

c. for which shear & deformation are related as τ = μ ∂u / ∂y

Question 266

Which of the following equations applies to the fluid flow through a packed bed for very large Reynolds number ?

a. Fanning equation
b. Blake-Pllummer equation
c. Hagen-Poiseulle equation
d. Kozney-Karman equation

Answer 266

b. Blake-Pllummer equation

Question 266

In case of end to end connection of two or more pipes in series, the __________ each pipe.

a. same rate of flow passes through
b. head loss is same through
c. rate of flow in each pipe is proportional to the length of
d. total flow rate is the sum of flow rate in

Answer 266

a. same rate of flow passes through

Question 267

The flow of gas along a pipe in the direction of decreasing pressure causes decrease in its

a. viscosity
b. specific volume
c. velocity
d. none of these

Answer 267

b. specific volume

Question 268

Centrifugal pump can’t be used to pump

a. molten sodium (used as a coolant in Fast Breeder Reactor).
b. moderately viscous vegetable oil used in soap industry.
c. thick molten soap at 80°C.
d. none of the above.

Answer 268

c. thick molten soap at 80°C.

Question 269

A stream line is

a. fixed in space in steady flow.
b. always the path of particle.
c. drawn normal to the velocity vector at every point.
d. a line connecting the mid points of flow cross-section.

Answer 269

a. fixed in space in steady flow.

Question 270

Quicksand is an example of a __________ fluid.

a. bingham plastic
b. dilatent
c. Newtonion
d. pseudoplastic

Answer 270

b. dilatent

Question 271

Correction for capillary effect in manometers (used for pressure measurement) need not be applied, if diameter of the manometer tube is __________ mm.

a. < 4
b. > 4
c. > 12.5
d. < 10

Answer 271

c. > 12.5

Question 272

Differential manometer measures the

a. absolute pressure
b. gauge pressure
c. pressure difference
d. pressure gradient

Answer 272

c. pressure difference

Question 273

The pressure and power requirement of a gas fan at constant speed & capacity varies __________ the gas density.

a. directly as
b. inversely as square root of
c. inversely as
d. as square of

Answer 273

a. directly as

Question 274

Isothermal turbulent flow of a fluid results in decrease of its pressure, which depends on the

a. wall roughness.
b. Reynolds number.
c. both (a) & (b).
d. neither (a) nor (b).

Answer 274

c. both (a) & (b).

Question 275

Boundary layer thickness in laminar flow over a flat plate increases as(where, d = distance from the leading edge.)

a. √d
b. d^(1/3)
c. d^2
d. d^(2/3)

Answer 275

a. √d

Question 276

Gradually varied flow in open channel is a/an __________ flow.

a. steady uniform
b. steady non-uniform
c. unsteady uniform
d. unsteady non-uniform

Answer 276

b. steady non-uniform

Question 277

The line of action of the buoyant force acts through the

a. centroid of the displaced volume of fluid.
b. centre of gravity of a submerged body.
c. centroid of the volume of any floating body.
d. none of these.

Answer 277

a. centroid of the displaced volume of fluid.

Question 278

Cavitation in a centrifugal pump can be avoided by keeping the

a. inlet pressure high
b. outlet pressure low
c. inlet pressure low
d. outlet pressure high

Answer 278

a. inlet pressure high

Question 279

Vane anemometer

a. is an area meter.
b. is a variable head meter.
c. rotates an element at a speed determined by the velocity of the fluid in which the meter is immersed.
d. none of these.

Answer 279

c. rotates an element at a speed determined by the velocity of the fluid in which the meter is immersed.

Question 280

The peripherial velocity at inlet of a centrifugal pump having inlet diameter of 25 cms and rotating at 950 rpm is __________ m/sec.

a. 1.8
b. 12.4
c. 186.2
d. 736.4

Answer 280

b. 12.4

Question 281

Laminar flow is characterised by the nonexistence of

a. pressure fluctuation.
b. eddies.
c. deviating velocities.
d. all (a), (b)&(c).

Answer 281

d. all (a), (b)&(c).

Question 282

The length of the tube necessary for the boundary layer to reach the centre of the tube and for fully developed flow to be established is called the __________ length.

a. equivalent
b. transition
c. Prandtl mixing
d. none of these

Answer 282

b. transition

Question 283

Select the correct practical example of steady non-uniform flow.

a. Motion of water around a ship in a lake.
b. Motion of river around bridge piers.
c. Steadily decreasing flow through a reducing section.
d. Steadily increasing flow through a pipe.

Answer 283

c. Steadily decreasing flow through a reducing section.

Question 284

Hydraulic diameter for non-circular ducts is equal to __________ times the area of flow divided by the perimeter.

a. two
b. three
c. four
d. eight

Answer 284

c. four

Question 285

Terminal velocity is

a. a constant velocity with no acceleration.
b. a fluctuating velocity.
c. attained after moving one-half of total distance.
d. none of these.

Answer 285

a. a constant velocity with no acceleration.

Question 286

Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement.

a. f1 = f2
b. f1 < f2
c. f1 > f2
d. data not sufficient to relate f1 & f2

Answer 286

c. f1 > f2

Question 287

For an incompressible fluid, the bulk modulus of elasticity is

a. 5 kg/m3
b. ∞ N/m2
c. 1 N
d. 0 N/m

Answer 287

b. ∞ N/m2

Question 288

A fluid is a substance, that

a. has to be kept in a closed container.
b. is almost incompressible.
c. has zero shear stress.
d. flows when even a small shear is applied to it.

Answer 288

d. flows when even a small shear is applied to it.

Question 289

The pressure intensity is the same in all directions at a point in a fluid

a. only when the fluid is frictionless.
b. only when the fluid is at rest having zero velocity.
c. when there is no motion of one fluid layer relative to an adjacent layer.
d. regardless of the motion of one fluid layer relative to an adjacent layer.

Answer 289

c. when there is no motion of one fluid layer relative to an adjacent layer.

Question 290

Which of the following must be followed by the flow of a fluid (real or ideal)?
(I) Newton’s law of viscosity.
(II) Newton’s second law of motion.
(III) The continuity equation.
(IV) Velocity of boundary layer must be zero relative to boundary.
(V) Fluid cannot penetrate a boundary.

a. I, II, III
b. II, III, V
c. I, II, V
d. II, IV, V

Answer 290

b. II, III, V

Question 291

Mach number is defined as the ratio of the local flow velocity to the sonic velocity in the fluid. For what value of Mach number, the gases are considered incompressible ?

a. < 0.3
b. > 3
c. 50
d. 1

Answer 291

a. < 0.3

Question 292

Boundary layer exists in flow

a. of real fluids.
b. over flat surfaces only.
c. in pipes only.
d. of ideal fluids only.

Answer 292

a. of real fluids.

Question 293

Rubber latex is an example of __________ fluid.

a. dilatent
b. Newtonion
c. pseudoplastic
d. Bingham plastic

Answer 293

c. pseudoplastic

Question 294

Velocity head on sudden enlargement in a horizontal pipe is converted into __________ head.

a. elevation
b. pressure
c. both (a) & (b)
d. neither (a) nor (b)

Answer 294

b. pressure

Question 295

The frictional resistance in laminar flow does not depend on the

a. area of surface in contact.
b. flow velocity.
c. fluid temperature.
d. pressure of flow.

Answer 295

a. area of surface in contact.

Question 296

A venturimeter measures the

a. velocity head
b. pressure
c. point velocity
d. none of these

Answer 296

d. none of these

Question 297

Gradually varying fluid flow is an example of __________ flow.

a. non-steady uniform
b. non-steady non-uniform
c. steady uniform
d. steady non-uniform

Answer 297

a. non-steady uniform

Question 298

Drag is the force component exerted on an immersed object,

a. passing the centroid of the body at 60°to the direction of motion.
b. the component being parallel to theflow direction.
c. the component being normal to the flow direction.
d. none of these.

Answer 298

b. the component being parallel to theflow direction.

Question 299

To handle smaller quantity of fluid at higher discharge pressure, use a __________ pump.

a. reciprocating
b. centrifugal
c. volute
d. rotary vacuum

Answer 299

a. reciprocating

Question 300

Cocks are used to control

a. water
b. any liquid
c. solids
d. none of these

Answer 300

b. any liquid

Question 301

The dimension of surface tension is

a. ML^-2
b. MT^-2
c. MLT^-2
d. ML^-2T

Answer 301

b. MT^-2

Question 302

Pick out the correct statement.

a. Fanning friction factor is inversely proportional to Reynolds number always.
b. The property of a randomly packed bed (with raschig rings) is given by the ratio of the total volume to the volume of voids in the bed.
c. Mach number in an incompressible fluid is always unity.
d. Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow.

Answer 302

d. Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow.

Question 303

The friction factor is

a. always inversely proportional to the Reynolds number.
b. not dimensionless.
c. not dependent on the roughness of the pipe.
d. none of these.

Answer 303

d. none of these.

Question 304

Rubber latex is an example of a __________ .fluid.

a. pseudoplastic
b. bingham plastic
c. dilatent
d. Newtonion

Answer 304

a. pseudoplastic

Question 305

Which of the following factors does not contribute to the pressure drop in a pipeline ?

a. Velocity of fluid
b. Size of pipe
c. Length of pipe and number of bends
d. None of these

Answer 305

d. None of these

Question 306

The phenomenon occuring during pumping of a liquid solution containing dissolved gases, which may come out of the solution giving rise to gas pockets, is termed as

a. evaporation
b. cavitation
c. sublimation
d. stripping

Answer 306

b. cavitation

Question 307

Working of a __________ pump characterises mixed flow.

a. turbine
b. piston
c. diaphragm
d. none of these

Answer 307

a. turbine

Question 308

The equivalent diameter for pressure drop calculation for a fluid flowing through a rectangular cross-section channels having sides ‘x’ & ‘y’ is given by

a. 2xy / x+y
b. xy / x+y
c. x+y / 2xy
d. x+y / xy

Answer 308

a. 2xy / x+y

Question 309

The rate of change of moment of momentum represents the __________ by the fluid.

a. torque applied
b. force exerted
c. work done
d. power developed

Answer 309

a. torque applied

Question 310

Cd for the orifice plate varies from

a. 0.58 to 0.8
b. 0.93 to 0.98
c. 0.2 to 0.3
d. 0.02 to 0.03

Answer 310

a. 0.58 to 0.8

Question 311

The discharge through a V-notch weir varies as

a. H^3/2
b. H^1/2
c. H^5/2
d. H^2/3

Answer 311

c. H^5/2

Question 312

Water flow rate in a pipe of 3.5 metres diameter can be most economically and conveniently measured by a/an

a. pitot tube
b. venturimeter
c. orificemeter
d. rotameter

Answer 312

a. pitot tube

Question 313

The specific speed of a pump is defined as the speed of a unit of such a size, that it

a. delivers unit discharge at unit head.
b. requires unit power for unit head.
c. delivers unit discharge at unit power.
d. none of these.

Answer 313

a. delivers unit discharge at unit head.

Question 314

In case of venturimeters, friction losses are about __________ percent of maximum velocity head.

a. 2
b. 8
c. 12
d. 20

Answer 314

a. 2

Question 315

With increase in the schedule number of a pipe of a particular nominal size, the

a. wall thickness also increases.
b. I.D. of the pipe decreases.
c. O.D. of the pipe remains constant.
d. all (a), (b) and (c)

Answer 315

d. all (a), (b) and (c)

Question 316

Turbine impeller

a. produces only radial current.
b. produces only tangential current.
c. is effective over wide range of viscosities.
d. does not produce tangential current.

Answer 316

c. is effective over wide range of viscosities.

Question 317

Friction produced by the formation of wakes is called the __________ friction.

a. disk
b. skin
c. form
d. none of these

Answer 317

c. form

Question 318

Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency)

a. ηma x ηm x ηv = ηo
b. ηm = ηv . ηma
c. ηma = ηm x ηv
d. ηv = ηm x ηma

Answer 318

b. ηm = ηv . ηma

Question 319

When the pipe Reynold’s number is 6000, the flow is generally

a. viscous
b. laminar
c. turbulent
d. transition

Answer 319

c. turbulent

Question 320

Fanning equation is given by
ΔP / ρ = 4f . L/D . v^2 / 2gc
It is applicable to __________ region flow.

a. transition
b. laminar
c. turbulent
d. both (b) and (c)

Answer 320

d. both (b) and (c)

Question 321

With a constant diameter impeller of a centrifugal pump

a. its capacity varies directly as the square of speed.
b. head varies as the square of speed.
c. horsepower input varies as the square of speed.
d. head varies as the speed.

Answer 321

b. head varies as the square of speed.

Question 322

For water, when the pressure increases, the viscosity

a. also increases
b. decreases
c. remains constant
d. first decreases, and then increases

Answer 322

d. first decreases, and then increases

Question 323

The head loss due to sudden expansion is

a. V1^2 - V2^2 / 2gc
b. (V1-V2)^2 / 2gc
c. V1-V2 / 2gc
d. V1^1 - V2^2 / gc

Answer 323

b. (V1-V2)^2 / 2gc

Question 324

Location of vena-contracta in an orificemeter does not depend upon the

a. type of orifice.
b. density, viscosity & compressibility of the fluid.
c. ratio of pipe diameter to orifice diameter.
d. pipe roughness.

Answer 324

a. type of orifice.

Question 325

At low Reynolds number

a. viscous forces are unimportant.
b. viscous forces control.
c. viscous forces control and inertial forces are unimportant.
d. gravity forces control.

Answer 325

c. viscous forces control and inertial forces are unimportant.

Question 326

For laminar flow through a closed conduit

a. Vmax = 2Vav
b. Vmax = Vav
c. Vmax = 1.5Vav
d. Vmax = 0.5Vav

Answer 326

a. Vmax = 2Vav

Question 327

In Newton’s law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass varies as the __________ of its diameter.

a. inverse
b. square root
c. second power
d. first power

Answer 327

b. square root

Question 328

Unsteady uniform flow is represented by flow through a/an

a. long pipe at constant rate.
b. long pipe at decreasing rate.
c. expanding tube at increasing rate.
d. expanding tube at constant rate.

Answer 328

b. long pipe at decreasing rate.

Question 329

If Blausius or Darcey friction factor is ‘f1’ then the Fanning friction factor is equal to

a. f1/4
b. 4f2
c. 2f1
d. f1/2

Answer 329

a. f1/4

Question 330

Pick out the wrong statement pertaining to fluid flow.

a. The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
b. The Newtonion fluid velocity in a circular pipe flow is maximum at the centre of the pipe.
c. Navier-Stokes equation is applicable to the analysis of viscous flows.
d. Hagen-Poiseuille equation is applicable to the laminar flow of Newtonion fluids.

Answer 330

a. The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.

Question 331

A Newtonion liquid (ρ = density, μ = viscosity) is flowing with velocity v in a tube of diameter ‘D’. Let Δp be the pressure drop across the length ‘L’. For a laminar flow, Δp is proportional to

a. L ρv2/D
b. L μ;V/D2
c. D ρv2/L
d. μ V/L

Answer 331

a. L ρv2/D

Question 332

While starting a centrifugal pump, its delivery valve should be kept

a. opened.
b. closed.
c. either opened or closed ; it does not make any difference.
d. either opened or closed; depending on the fluid viscosity.

Answer 332

b. closed.

Question 333

For flow past a flat plate, if x is the distance along the plate in the direction of flow, the boundary layer thickness is proportional to

a. √x
b. 1/√x
c. x
d. 1/x

Answer 333

a. √x

Question 334

Velocity at a certain point in case of streamline flow is

a. constant
b. independent of time
c. both (a) & (b)
d. neither (a) nor (b)

Answer 334

c. both (a) & (b)

Question 335

Sewage sludge is an example of the __________ fluid.

a. Bingham plastic
b. Newtonion
c. pseudoplastic
d. dilatent

Answer 335

a. Bingham plastic

Question 336

In case of a rotameter, the density of the float material is __________ that of the liquid it replaces.

a. more than
b. less than
c. equal to
d. either (a) or (b)

Answer 336

a. more than

Question 337

Multistage centrifugal pumps are generally used for

a. high head.
b. low head but high discharge.
c. highly viscous liquid.
d. slurries of high solid concentration.

Answer 337

a. high head.

Question 338

The fluid jet discharging from a 2” diameter orifice has a diameter of 1.75” at its vena-contracta. The co-efficient of contraction is

a. 1.3
b. 0.766
c. 0.87
d. none of these

Answer 338

b. 0.766

Question 339

A bed consists of particles of density 2000 kg/m3. If the height of the bed is 1.5 metres and its porosity 0.6, the pressure drop required to fluidise the bed by air is

a. 25.61 kPa
b. 11.77 kPa
c. 14.86 kPa
d. 21.13 kPa

Answer 339

b. 11.77 kPa

Question 340

Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation ?

a. Decrease in effect
b. Increase in thrust
c. Develops noise
d. Develops high pressure

Answer 340

d. Develops high pressure

Question 341

For a specific centrifugal air blower operating at constant speed & capacity, the power requirement and pressure vary

a. directly as square of gas density.
b. directly as gas density.
c. directly as square root of gas density.
d. inversely as gas density.

Answer 341

b. directly as gas density.

Question 342

Capillary tube method of viscosity measurement is based on the

a. Hagen-Poiseulle’s equation
b. Stoke’s law
c. Navier-stokes equation
d. none of these

Answer 342

a. Hagen-Poiseulle’s equation

Question 343

It is possible to integrate an automatic flow controller to a

a. flow nozzle
b. venturimeter
c. rotameter
d. none of these

Answer 343

c. rotameter

Question 344

For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is

a. more
b. less
c. equal
d. independent of porosity

Answer 344

b. less

Question 345

For a reciprocating pump, the indicator diagram is the graph between the

a. discharge and overall efficiency.
b. volume swept by piston for one complete revolution and the pressure in the cylinder.
c. angle swept by the crank pin at any instant and the discharge.
d. none of these.

Answer 345

b. volume swept by piston for one complete revolution and the pressure in the cylinder.

Question 346

The most important factor, which determines the maximum height to which water can be lifted by a pump at standard temperature is the

a. barometric pressure
b. speed of the impeller
c. diameter of the impeller
d. both (b) and (c)

Answer 346

a. barometric pressure

Question 347

High specific speed of a pump implies that, it is a/an __________ pump.

a. centrifugal
b. mixed flow
c. axial flow
d. none of these

Answer 347

c. axial flow

Question 348

A gas (density = 1.5 kg/m3 , viscosity = 2x 10-5 kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5kg/m3and viscosity of 3 x 10-5kg/m.s flowing at 3 m/s will be

a. 8400 Pa/m
b. 12600 Pa/m
c. 18900 Pa/m
d. 16800 Pa/m

Answer 348

b. 12600 Pa/m

Question 349

One poise (unit of absolute/dynamic viscosity) is equivalent to one

a. gm/cm^2. sec.
b. gm/cm. sec.
c. cm^2/sec.
d. m^2/sec.

Answer 349

b. gm/cm. sec.

Question 350

The equation relating friction factor to Reynold number, f-0.5 = 4 loge (NRe/f)-0.4, is called the __________ equation.

a. Nikuradse
b. Von-Karman
c. Blausius
d. Colebrook

Answer 350

a. Nikuradse

Question 351

Pressure drop for turbulent fluid flow through a circular pipe is given by

a. 64/Re
b. 32μLV / gc D^2
c. 4f . L/D . v^2/2gc . ρ
d. f . L/D . ρ . v^2/2gc

Answer 351

c. 4f . L/D . v^2/2gc . ρ

Question 352

What is the co-efficient of contraction, if a fluid jet discharging from a 50 mm diameter orifice has a 40 mm diameter at its vena-contracta ?

a. 0.64
b. 1.65
c. 0.32
d. 0.94

Answer 352

a. 0.64

Question 353

For an unstable equilibrium of a floating body (where, M = metacentre.)

a. M is above G
b. M is below G
c. M & G coincide
d. none of these

Answer 353

b. M is below G

Question 354

Which of the following can be used for the direct measurement of volumetric flow rate of slurry ?

a. Venturimeter
b. Orificemeter
c. Rotameter
d. Pitot tube

Answer 354

c. Rotameter

Question 355

A pipe is defined as ‘hydraulically smooth’, if the friction factor

a. is not a function of Reynolds number.
b. for a given Reynolds number remains constant even on further smoothening of the pipe.
c. is zero irrespective of the Reynolds number.
d. none of these.

Answer 355

b. for a given Reynolds number remains constant even on further smoothening of the pipe.

Question 356

A Pitot tube indicates 5 cm of water (manometer) when it is being used for measuring velocity of air. The velocity of air in m/sec is

a. 5
b. 14.1
c. 56.22
d. 28.2

Answer 356

d. 28.2

Question 357

Delivery of insufficient quantity of liquid by a pump may be caused by

a. air leak in the inlet
b. low rpm
c. too high a lift
d. all (a), (b) and (c)

Answer 357

d. all (a), (b) and (c)

Question 358

Fluid resistance to shear depends upon its

a. rate of transfer of molecular momentum.
b. cohesion.
c. both (a) and (b).
d. neither (a) nor (b).

Answer 358

c. both (a) and (b).

Question 359

In case of a __________ the energy of flow is considerably decreased downstream of the machine.

a. blower
b. turbine
c. centrifugal pump
d. centrifugal fan

Answer 359

b. turbine

Question 360

With increase in the shear rate, the apparent viscosity of pseudoplastic fluids

a. increases
b. decreases
c. remains same
d. may increase or decrease; depends on the magnitude of shear rate

Answer 360

b. decreases

Question 361

Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about

a. 0.42
b. 0.62
c. 0.82
d. 0.98

Answer 361

b. 0.62

Question 362

Purpose of hydraulic accumulator is to

a. ensure intermittant supply of hydraulic pressure.
b. increase the pressure and store/ accumulate it.
c. accumulate pressure to increase force.
d. generate high pressure to operate hydraulic machines like cranes, lifts, presses etc

Answer 362

d. generate high pressure to operate hydraulic machines like cranes, lifts, presses etc

Question 363

Pick out the wrong statement.

a. Surface tension of a liquid is because of the difference in magnitude of adhesive & cohesive forces.
b. A hydrometer used for the determination of specific gravities of liquids works on the principle of buoyant forces.
c. In case of unsteady fluid flow, the velocity at any given point does not change with time.
d. Turbulent fluid flow is characterised by the rapid fluctuation of instantaneous pressure & velocity at a point.

Answer 363

c. In case of unsteady fluid flow, the velocity at any given point does not change with time.

Question 364

Purpose of relief valve in a reciprocating pump is to

a. protect the pump against developing excessive pressure.
b. facilitate unidirectional flow of liquid.
c. reduce the discharge pressure.
d. control the rate of discharge.

Answer 364

a. protect the pump against developing excessive pressure.

Question 365

Select the correct statement.

a. The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter.
b. A venturimeter with a given gage difference discharges at a greater rate, when the flow is vertically downward through it, than when the flow is vertically upward.
c. For a given pressure difference, the discharge of gas is greater through a venturimeter, when compressibility is taken into account, than when it is neglected.
d. The overall pressure loss is the same in a given pipe line, whether a venturimeter or a nozzle with the same throat dia is used.

Answer 365

a. The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter.

Question 366

The Kozney-Carman equation, rewritten in terms of non-dimensional numbers gives (ΔP/pu2 ) proportional to

a. L/Dp / Re
b. Re / Dp/L
c. L/Dp / Re^2
d. Re^2 / Dp/L

Answer 366

a. L/Dp / Re

Question 367

In case of turbulent flow of fluid through a circular pipe, the

a. mean flow velocity is about 0.5 times the maximum velocity.
b. velocity profile becomes flatter and flatter with increasing Reynolds number.
c. point of maximum instability exists at a distance of 2r/3 from the pipe wall (r = pipe radius).
d. skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.

Answer 367

d. skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.

Question 368

For the same terminal conditions and valve size, the pressure drop in a fully opened globe valve as compared to that in a gate valve is

a. more
b. less
c. equal
d. either (a) or (b); depends on the viscosity of the fluid

Answer 368

a. more

Question 369

Steady fluid flow occurs, when the derivative of flow variables satisfy the following condition.

a. ∂ / ∂s = 0
b. ∂ / ∂t = 0
c. ∂ / ∂s = constant
d. ∂ / ∂t = constant

Answer 369

b. ∂ / ∂t = 0

Question 370

What is the maximum theoretical suction lift (metres) of a reciprocating pump ?

a. 5
b. 10
c. 50
d. 100

Answer 370

b. 10

Question 371

The terminal velocity of a particle moving through a fluid varies as dp^n. The value of n is equal to __________ in Stoke’s law regime.

a. 1
b. 0.5
c. 2
d. 1.5

Answer 371

c. 2

Question 372

Function of air vessel provided in a reciprocating pump is to

a. reduce discharge fluctuation.
b. reduce the danger of cavitation.
c. avoid the necessity of priming.
d. increase the pump efficiency.

Answer 372

a. reduce discharge fluctuation.

Question 373

The Prandtl pitot tube measures the

a. velocity at a point in the flow.
b. pressure at a point.
c. average flow velocity.
d. pressure difference in pipe flow.

Answer 373

a. velocity at a point in the flow.

Question 374

Pressure drop in packed bed for turbulent flow is given by the __________ equation.

a. Kozney-Karman
b. Blake-Plummer
c. Leva’s
d. Hagen-Poiseulle’s

Answer 374

b. Blake-Plummer

Question 375

In the complete turbulence zone (in rough pipes), the

a. rough and smooth pipes have the same friction factor.
b. laminar film covers the roughness projections.
c. friction factor depends upon NRe only.
d. friction factor is independent of the relative roughness.

Answer 375

d. friction factor is independent of the relative roughness.

Question 376

Which of the following has the minimum compressibility ?

a. Water at room temperature
b. Air at room temperature
c. Oxygen at room temperature
d. Nitrogen at room temperature

Answer 376

a. Water at room temperature

Question 377

In case of centrifugal fan or blower, the gas capacity varies as

a. speed
b. (speed)^2
c. (speed)^3
d. (speed)^0.5

Answer 377

a. speed

Question 378

Pick out the wrong statement.

a. A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocity.
b. Newton’s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution.
c. Laminar flow of viscous liquids is involved in the lubrication of various types of bearings.
d. Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes.

Answer 378

b. Newton’s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution.

Question 379

Pick out the wrong statement.

a. In a static mass of liquid, the pressure at a point is the same for all liquids.
b. Pressure decreases exponentially with elevation in an isothermal atmosphere.
c. Atmospheric pressure = absolute pressure-gage pressure.
d. As per Pascal’s law, the pressure at a point in a static or uniformly moving fluid is equal in all directions.

Answer 379

a. In a static mass of liquid, the pressure at a point is the same for all liquids.

Question 380

The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is

a. parabolic
b. flat
c. flat near the wall and parabolic in the middle
d. parabolic near the wall and flat in the middle.

Answer 380

d. parabolic near the wall and flat in the middle.

Question 381

Fanning friction factor for laminar flow of fluid in a circular pipe is

a. not a function of the roughness of pipe wall.
b. inversely proportional to Reynolds number.
c. both (a) & (b).
d. neither (a) nor (b).

Answer 381

c. both (a) & (b).

Question 382

Mach number is the ratio of the speed of the

a. fluid to that of the light.
b. light to that of the fluid.
c. fluid to that of the sound.
d. sound to that of the fluid.

Answer 382

c. fluid to that of the sound.

Question 383

A piezometer opening measures the __________ fluid pressure.

a. static
b. undisturbed
c. total
d. dynamic

Answer 383

b. undisturbed

Question 384

Drag force on the float of a rotameter is(where Q = flow rate of the )

a. ∝Q
b. ∝Q
c. ∝Q2
d. constant

Answer 384

d. constant

Question 385

The unit of dynamic viscosity in SI unit is

a. kg/m . sec
b. N/m^2
c. m^2 /sec.
d. m/N. sec.

Answer 385

a. kg/m . sec

Question 386

Pressure drop (Δp) for a fluid flowing in turbulent flow through a pipe is a function of velocity (V) as

a. V^1.8
b. V^-0.2
c. V^2.7
d. V^2

Answer 386

d. V^2

Question 387

Dean number is concerned with the

a. fluid-particle interaction.
b. fluid flow through helical pipes.
c. power consumption in agitated vessels.
d. psychrometry.

Answer 387

b. fluid flow through helical pipes.

Question 388

The equation given below is called the __________ .

f^-0.5 = 4.07 loge (NRe√f)^-0.6

a. Colebrook formula
b. Von-Karman equation
c. Fanning equation
d. none of these

Answer 388

b. Von-Karman equation

Question 389

Poise is converted into stoke by

a. multiplying with density (gm/c.c).
b. dividing by density (gm/c.c).
c. multiplying with specific gravity.
d. dividing by specific gravity.

Answer 389

b. dividing by density (gm/c.c).

Question 390

The fluid velocity varies as the square root of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop fo __________ fluid.

a. dilatant
b. pseudoplastic
c. Bingham plastic
d. Newtonion

Answer 390

a. dilatant

Question 391

Kinetic energy of fluid per unit weight represented by the velocity head is given by

a. 2v^2/gc
b. v^2/2gc
c. ρv^2/gc
d. ρ.v^2/2gc

Answer 391

b. v^2/2gc

Question 392

At a constant speed of the centrifugal pump . it __________ the impeller diameter.

a. capacity varies directly with
b. head varies as the square of
c. horsepower varies as the cube of
d. all (a), (b) and (c)

Answer 392

d. all (a), (b) and (c)

Question 393

The pressure co-efficient is the ratio of pressure forces to __________ forces.

a. viscous
b. inertial
c. gravity
d. surface tension

Answer 393

a. viscous

Question 394

Vena-contracta formed during flow of a liquid through an orificemeter has

a. minimum liquid cross-section.
b. more diameter compared to orifice diameter.
c. minimum velocity of fluid stream.
d. none of these.

Answer 394

a. minimum liquid cross-section.

Question 395

Pick out the Blake-Plummer equation (valid for large NRe) for fluid flow through beds of solids.

a. Δp/ρ = 4f . L/D . v^2/2gc
b. fp = 150(1-ε)/NRe + 1.75
c. Δp . gc . D^2p. ε^3 / L . ˉvo . μ(1-ε)^2 = 150
d. Δp/δ . L . gc/v^2o . Dp ε^3 / 1-ε = 1.75

Answer 395

d. Δp/δ . L . gc/v^2o . Dp ε^3 / 1-ε = 1.75

Question 396

As per Newton’s law of viscosity, the shear stress for a given rate of angular deformation of fluid is proportional to(where, μ = fluid viscosity)

a. 1/μ
b. μ
c. μ^2
d. 1/μ^2

Answer 396

b. μ

Question 397

Horsepower increase of a centrifugal gas compressor without altering the volumetric flow rate will __________ the gas discharge pressure.

a. increase
b. decrease
c. not change
d. exponentially decrease

Answer 397

a. increase

Question 398

In continuous fluidisation

a. solids are completely entrained.
b. the pressure drop is less than that for batch fluidisation.
c. there is no entrainment of solids.
d. velocity of the fluid is very small.

Answer 398

a. solids are completely entrained.

Question 399

Glass pipes can be joined by

a. flanges
b. welding
c. soldering
d. bell and spigot joint

Answer 399

d. bell and spigot joint

Question 400

If two capillary tubes of dia 0.5 mm and 1 mm are dipped in a pot containing mercury, then the rise of mercury is

a. same in both the tubes.
b. greater in 1 mm dia tube.
c. greater in 0.5 mm dia tube.
d. zero in both the tubes.

Answer 400

c. greater in 0.5 mm dia tube.

Question 401

For laminar flow of a shear thinning liquid in a pipe, if the volumetric flow rate is doubled, the pressure gradient will increase by a factor of

a. 2
b. <2
c. >2
d. 1/2

Answer 401

a. 2

Question 402

Weber number is the ratio of inertial force to __________ force.

a. surface tension
b. gravity
c. viscous
d. elastic

Answer 402

a. surface tension

Question 403

The curve of metacentre for a floating body __________ the curve of buoyancy.

a. is always below
b. is the evolute of
c. intersects at right angle
d. is tangential to

Answer 403

b. is the evolute o

Question 404

At what value of crank angle (roughly), no flow of water from or into the air vessel takes place in case of a double acting reciprocating pump ?

a. 40° and 140°
b. 45° and 60°
c. 90° and 80°
d. 20° and 120°

Answer 404

a. 40° and 140°

Question 405

The range of a particular rotameter can be increased by

a. use of floats of different densities.
b. no means.
c. increasing the diameter of the float.
d. decreasing the diameter of the float.

Answer 405

a. use of floats of different densities.

Question 406

Which of the following is dimensionless ?

a. Angular velocity
b. Fanning friction factor
c. Specific volume
d. None of these

Answer 406

b. Fanning friction factor

Question 407

A liquid is pumped at the rate of 600 litres using 1000 rpm. If the rpm is changed to 1100, the liquid pumped is __________ litres.

a. 600
b. 660
c. 1.1
d. 60

Answer 407

b. 660

Question 408

A compressor that takes suction at a pressure below atmospheric and discharge against atmospheric pressure is called a __________ pump.

a. sump
b. volute
c. vacuum
d. submerged

Answer 408

c. vacuum

Question 409

A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun’s equation for the above fluid-particle system (in SI units) is given below :
Δ P/L = 375 x 10^3 VOM + 10.94 x 10^6 V^2OM (SI units)
If water is to be used as the fluidising medium, in actual operation, the above bed has a height = 1 m. What is the porosity of the fluidised bed ?

a. 0.2
b. 0.5
c. 0.7
d. 0.8

Answer 409

c. 0.7

Question 410

Dimension of kinematic viscosity is

MLT^-1
L^2 . T^-1
L^2T
L^2 . T^-2

Answer 410

L^2 . T^-1

Question 411

A streamline is a line in flow field,

a. that is traced by all the fluid particles passing through a given point.
b. along which a fluid particle travels.
c. such that at every point on it, the velocity is tangential to it.
d. none of these.

Answer 411

c. such that at every point on it, the velocity is tangential to it.

Question 412

While starting an axial flow pump, its delivery valve should be kept

a. open
b. closed
c. either open or closed
d. none of these

Answer 412

b. closed

Question 413

__________ forces do not act in case of fluid flow.

a. Elastic
b. Tensile
c. Vibratory
d. Centrifugal

Answer 413

b. Tensile

Question 414

Non-colloidal solution is an example of the __________ fluid.

a. non-Newtonion
b. Newtonion
c. dilatent
d. pseudoplastic

Answer 414

b. Newtonion

Question 414

Boundary layer separation is caused by the

a. reduction of pressure below vapour pressure.
b. reduction of pressure gradient to zero.
c. adverse pressure gradient.
d. reduction of boundary layer thickness to zero.

Answer 414

c. adverse pressure gradient.

Question 414

Pumping of a corrosive liquid is generally preferred to be done by a __________ pump, as it can be made of a variety of materials including plastics.

a. piston
b. gear
c. positive displacement
d. sump

Answer 414

b. gear

Question 414

Identification of pipelines carrying different liquids and gases is done by the __________ of the pipe.

a. diameter
b. colour
c. altitude
d. none of these

Answer 414

b. colour

Question 414

A 2” gate valve fitted in a pipe is replaced by a similar globe valve. Pressure drop in gate valve was Δp. For the same discharge, the pressure drop across globe valve is

a. Δp
b. < Δp
c. > Δp
d. Δp2

Answer 414

c. > Δp

Question 414

Pick out the correct statement.

a. Human blood is a Newtonion fluid.
b. A Newtonion fluid obeys Newton’s law of cooling.
c. For a non-Newtonion fluid, a straight line passes through the origin in a plot between shear stress and shear gradient.
d. Thin lubricating oil is an example of a non-Newtonion fluid.

Answer 414

b. A Newtonion fluid obeys Newton’s law of cooling.

Question 415

What is the unit of kinematic viscosity in SI unit ?

a. M^2/sec
b. N/m^2 . sec
c. Kg . sec/m
d. None of these

Answer 415

a. M^2/sec

Question 415

Hydraulic __________ works on the principle of Pascal’s law of transmission of fluid pressure.

a. press
b. turbine
c. pump
d. coupling

Answer 415

a. press

Question 415

The contraction co-efficient for Borda’s mouthpiece (for frictionless fluid) is

a. 0.1
b. 0.5
c. 0.94
d. 1

Answer 415

b. 0.5

Question 415

Potential function is applicable only for __________ flow.

a. irrotational
b. turbulent
c. steady
d. none of these

Answer 415

a. irrotational

Question 415

Purpose of air lift pump is to

a. compress air.
b. lift compressed air.
c. lift water from a well by using compressed air.
d. lift air under negative pressure.

Answer 415

c. lift water from a well by using compressed air.

Question 415

Two piping system are said to be equivalent, when the __________ are same.

a. fluid flow rate & friction loss
b. length & friction factor
c. diameter & friction factor
d. length & diameter

Answer 415

a. fluid flow rate & friction loss

Question 415

Pick out the correct statement pertaining to venturimeter.

a. A venturimeter with a fixed pressure drop discharges more, when the flow is vertically downward, than when the flow is vertically upward.
b. The co-efficient of contraction of a venturimeter is always unity.
c. For a fixed pressure drop, the discharge of a gas through a venturimeter is greater, when compressibility is taken into account, than when it is neglected.
d. none of these.

Answer 415

d. none of these.

Question 415

For very low pressure and high discharge rate, the compressor used is a/an __________ compressor.

a. axial
b. reciprocating
c. rotary
d. none of these

Answer 415

c. rotary

Question 415

The main factor on which the behaviour of a mass of fluidised solid depends mainly is the

a. fluid characteristics
b. particle size
c. both (a) and (b)
d. neither (a) nor (b)

Answer 415

c. both (a) and (b)

Question 416

What is the speed of sound (m/sec) in ordinary water ?

a. 1500
b. 330
c. 1000
d. 3000

Answer 416

a. 1500

Question 417

Which of the following exemplifies a three dimensional fluid flow ?

a. Fluid flow at the inlet to a nozzle
b. Fluid flow between parallel plates
c. Viscous fluid flow between converging plates
d. None of these

Answer 417

a. Fluid flow at the inlet to a nozzle

Question 418

Volute of a centrifugal pump should be designed in a fashion, such that the

a. kinetic head gets converted into static head.
b. moving stream gradually reduces velocity.
c. mean velocity remains constant.
d. none of these.

Answer 418

a. kinetic head gets converted into static head.

Question 419

The head loss due to sudden contraction is proportional to

a. velocity
b. velocity head
c. turbulence
d. none of these

Answer 419

b. velocity head

Question 420

Cavitation occurs in a centrifugal pump when the suction pressure is

a. less than the vapour pressure of the liquid at that temperature.
b. greater than the vapour pressure of the liquid at that temperature.
c. equal to the vapour pressure.
d. equal to the developed head.

Answer 420

a. less than the vapour pressure of the liquid at that temperature.

Question 421

An ideal plastic substance indicates no deformation, when stressed upto yield stress, but behaves like a Newtonion fluid beyond yield stress. Which of the following is an ideal plastic ?

a. Sewage sludge
b. Rubber latex
c. Blood
d. Sugar solution

Answer 421

a. Sewage sludge

Question 422

The capacity of a centrifugal pump Can be increased by increasing the

a. impeller diameter or speed.
b. number of pumps and joining them in series,
c. number of pumps and joining them in parallel.
d. all (a), (b) and (c).

Answer 422

d. all (a), (b) and (c).

Question 423

Which law is followed by the velocity distribution in the turbulent boundary layer?

a. Parabolic law
b. Linear law
c. Logarithmic law
d. None of these

Answer 423

c. Logarithmic law

Question 424

The losses in open channel flow generally vary as the

a. inverse of the roughness.
b. first power of the roughness.
c. square of the velocity.
d. inverse square of hydraulic radius.

Answer 424

b. first power of the roughness.

Question 425

Rise of liquid in a capillary tube is due to

a. cohesion
b. adhesion
c. both (a) & (b)
d. neither (a) nor (b)

Answer 425

c. both (a) & (b)

Question 426

Out of the following flow measuring devices, which one incurs the maximum installation cost as well as pressure loss ?

a. Flow nozzle
b. Venturimeter
c. Rotameter
d. Orificemeter

Answer 426

b. Venturimeter

Question 427

For turbulent fluid flow in pipe, the expression for Prandtl one seventh power law is (where, r= pipe radius, x = distance).

a. V/Vmax = (x/r)^1/7
b. V/Vmax = (r/x)^1/7
c. V/Vmax = (x.r)^1/7
d. none of these

Answer 427

a. V/Vmax = (x/r)^1/7

Question 428

Which of the following has the maximum compression ratio ?

a. Blower
b. Compressor
c. Vacuum pump
d. Fan

Answer 428

c. Vacuum pump

Question 429

Scale up of agitator design requires

a. geometrical similarity only.
b. dynamic similarity only.
c. both geometrical and dynamic similarity.
d. all geometrical, dynamic and kinematic similarity.

Answer 429

d. all geometrical, dynamic and kinematic similarity.

Question 430

The actual velocity at vena-contracta for flow through an orifice from a reservoir is given by

a. Cv . √2gH
b. Cc . √2gH
c. Cd . √2 gH
d. Cv . Va

Answer 430

a. Cv . √2gH

Question 431

The head loss in turbulent flow in pipe is proportional to(where, V = velocity of fluid through the pipe)

a. V^2
b. 1/V^2
c. 1/V
d. V

Answer 431

a. V^2

Question 432

Unsteady non-uniform flow is represented by flow through a/an

a. long pipe at constant rate.
b. long pipe at decreasing rate.
c. expanding tube at increasing rate.
d. expanding tube at constant rate.

Answer 432

c. expanding tube at increasing rate.

Question 433

Prandtl number is a measure of the

a. heat conduction to viscosity of a fluid.
b. Cp/Cv of a fluid.
c. elastic force to pressure force in the fluid flow.
d. inertial force to elastic force in the fluid flow.

Answer 433

a. heat conduction to viscosity of a fluid.

Question 434

A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, then the new head will be __________ metres.

a. 2
b. 4
c. 8
d. 5.5

Answer 434

a. 2

Question 435

In hindered settling, the particles are

a. placed farther from the wall.
b. not affected by other particles and the wall.
c. near each other,
d. none of these.

Answer 435

c. near each other,

Question 436

section 10 cot’d