Momentum

Question 1

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

Answer 1

surface tension IE
cohesion CORRECT

Question 2

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

Answer 2

Jet pump

Question 3

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

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

Answer 3

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

Question 4

Head developed by a centrifugal pump depends on its

speed
impeller diameter
both (a) and (b)
neither (a) nor (b)

Answer 4

Both a and b

Question 5

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

Answer 5

mean velocity

Question 6

The head loss in turbulent flow in a pipe varies

Answer 6

as (velocity)2

Question 7

Most commonly used joint in the underground pipe lines is the

Answer 7

Sleevejoint

Question 8

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

Question 9

The net positive suction head (NPSH) of a centrifugal pump is defined as

Answer 9

sum of the velocity head and the pressure head at the suction minus vapor pressure of the liquid at suction temperature.

Question 10

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

Answer 10

monotonically decreases. IE

increases and then decreases. CORRECT

Question 11

The velocity profile for turbulent flow through a closed conduit is

Answer 11

For turbulent its logarithmic.

And for laminar its parabolic

Question 12

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

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

Answer 12

friction co-efficient for flows at equal Reynold number.

Question 13

Water hammer in a pipeline results from the

Answer 13

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

Question 14

Molten soap mass is transported by a __________ pump.

Answer 14

Gear pump

Question 15

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

Answer 15

Mach

Question 16

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

Answer 16

smaller than

Question 17

The terminal velocity of a small sphere settling in a viscous fluid varies as the
first power of its dimeter.
inverse of the fluid viscosity.
inverse square of the diameter.
square of the difference in specific weights of solid & fluid.

Answer 17

inverse of the fluid viscosity

Question 18

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

Answer 18

increases

Question 19

Foot valves provided in pumps are __________ valves.

Answer 19

directional control

Question 20

At high Reynolds number

Answer 20

inertial forces control and viscous forces are unimportant.

Question 21

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

Answer 21

more than

Question 22

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

Answer 22

0.5
Eq 6-239

Question 23

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

Answer 23

7 to 15
Convergent side 15 to 20 and divergent side 5 to 7 in venturi meter.

Question 24

The dimension of dynamic viscosity is

Answer 24

ML-1T-1

Question 25

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 same as that of A. one fourth as that of A. twice as that of A. four times as that of A.

Answer 25

one fourth as that of A.IE four times as that of A.

Question 26

The pitot static tube does not measure the __________ pressure. static total difference in static & dynamic all (a), (b) and (c)

Answer 26

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

Question 27

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

Answer 27

Newtonion

Question 28

In fluid flow, cavitation is caused, if the fluid velocity decreases to zero. total energy decreases. both (a) and (b). flow pressure approaches its vapor pressure at the prevailing temperature.

Answer 28

flow pressure approaches its vapor pressure at the prevailing temperature.

Question 29

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

Answer 29

2

Question 30

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).

Answer 30

0.44

Question 31

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) Vs/Dp2 Vs2/Dp2 Vs2/Dp3 Vs/Dp3

Answer 31

Vs/Dp2

Question 32

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

Answer 32

1000

Question 33

Co-efficient of velocity is __________ the coefficient of discharge. less than less than more than equal to not related to

Answer 33

More than

Question 34

All pipes of a particular nominal size have the same

Answer 34

outside diameter

Question 35

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

Answer 35

Diaphragm

Question 36

Which of the following is not concerned with the fluid-particle interaction ? Drag co-efficient Froude number Galileo number Weber number

Answer 36

Weber number

Question 37

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.

Answer 37

8

Question 38

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

Answer 38

both (b) and (c)

Question 39

Pressure drag does not depend upon the roughness of surface of the body. pressure of main flow only. length of the body in flow direction. all (a), (b) and (c)

Answer 39

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

Question 40

Dimension of absolute viscosity is

Answer 40

ML-1T-1 Dynamic is same as absolute Empirical same with kinematic

Question 41

__________ pumps are axial flow pumps. Turbine Propeller Diffuser none of these

Answer 41

Propeller

Question 42

Brownian movement is prominent in the particle size range of __________ microns in case of settling of a particle in a fluid. 2 to 3 0.01 to 0.10 200 to 300 100 to 1000

Answer 42

2 to 3

Question 43

For a particle settling in water at its terminal settling velocity, which of the following is true ? Buoyancy = weight + drag Weight = buoyancy + drag Drag = buoyancy + weight Drag = weight

Answer 43

Weight = buoyancy + drag

Question 44

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

Answer 44

20kPa

Question 45

Pick out the correct statement. A forced vortex occurs when fluid rotates as a solid about an axis. In laminar flow, Newton's law of viscosity does not apply. A free vortex occurs, when fluidrotates as a solid. In turbulent flow, there are neither cross-currents nor eddies.

Answer 45

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

Question 46

Shear stress in a fluid flowing in a round pipe

Answer 46

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

Question 47

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

Answer 47

tungsten

Question 48

Two dimensional stream function

Answer 48

is constant along a stream line.

Question 49

What causes cavitation in centrifugal pump ? High suction pressure Low barometric pressure Low suction pressure High suction velocity

Answer 49

Low suction pressure

Question 50

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

Answer 50

single stage vertical

Question 51

A hydraulic ram acts as a/an __________ pump.

Answer 51

impulse

Question 52

Pick out the wrong statement. The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonion fluids is In the equation, the value of 'n' for pseudoplastic and dilatant fluids are < 1 and >1 respectively. Shear stress for Newtonion fluid is proportional to the rate of shear in the direction perpendicular to motion. With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids.

Answer 52

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

Question 53

The line of action of the buoyant force passes through the centre of gravity of the submerged body. displaced volume of the fluid. volume of fluid vertically above the body. horizontal projection of the body.

Answer 53

displaced volume of the fluid.

Question 54

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

Answer 54

moving

Question 55

What causes convective acceleration in fluid flow ?

Answer 55

Non-uniformity of flow

Question 56

The Stoke's stream function applies to the irrotational flow only. ideal/non-viscous fluids only. cases of axial symmetry. none of these.

Answer 56

cases of axial symmetry.

Question 57

Slugging in a fluidised bed can be avoided by using tall narrow vessel. deep bed of of solids shallow beds of solids and proper choice of particle size. very large particles.

Answer 57

shallow beds of solids and proper choice of particle size.

Question 58

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

Answer 58

2

Question 59

The simple pitot tube measures the __________ pressure. static dynamic total none of these

Answer 59

Total

Question 60

Capacity of a hydraulic accumulator is defined in terms of maximum amount of energy stored. flow rate through accumulator. rate of falling of ram. volume available in the cylinder.

Answer 60

amount of energy stored.

Question 61

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.

Answer 61

1:2:2

Question 62

With diminishing cross-sectional area in case of subsonic flow in a converging nozzle, the velocity increases pressure decreases both (a) & (b) neither (a) nor (b)

Answer 62

both (a) & (b)

Question 63

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. Re << 1, accelerating flow Re >> 1, accelerating flow Re << 1, decelerating flow Re >>1, decelerating flow

Answer 63

Re >>1, decelerating flow

Question 64

Manometers measure the __________ pressure. vacuum as well as the atmospheric difference in absolute gage

Answer 64

difference in

Question 65

Which of the following fluid forces are not considered in the Navier-Stoke's equation? Gravity forces Viscous forces Pressure forces Turbulent forces

Answer 65

Turbulent forces 6-27 eqn

Question 66

Which of the following may be termed as a variable orifice flowmeter ? Rotameter Pitot tube V-notch All (a), (b) and (c)

Answer 66

Rotameter

Question 67

In turbulent flow, a rough pipe has the same friction factor as a smooth pipe in the zone of complete turbulence. when the roughness projections are much smaller than the thickness of the laminar film. everywhere in the transition zone. when the friction factor is independent of the Reynold's number.

Answer 67

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

Question 68

Air vessel provided in a reciprocating pump smoothens the flow by avoiding pulsations. increases the volumetric efficiency of the pump. saves the pump from the danger of cavitation. none of these.

Answer 68

none of these.

Question 69

Bernoulli's equation is dependent on the first law of thermodynamics. third law of thermodynamics. law of conservation of momentum. none of these.

Answer 69

first law of thermodynamics

Question 70

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

Answer 70

V/vmax =(x/r)^¹/⁷

Question 71

The capacity of an accumulator is the maximum

Answer 71

energy which it can store.

Question 72

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

Answer 72

0.5 d

Question 73

The pump impeller and the turbine runner in a hydraulic torque converter have the same diameter. have different diameters. are directly coupled. none of these.

Answer 73

have different diameters.

Question 74

Reciprocating pumps compared to centrifugal pumps deliver liquid at uniform pressure. can handle slurries more efficiently. are not subject to air binding. can be operated with delivery valve closed.

Answer 74

are not subject to air binding.

Question 75

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

Answer 75

surface tension

Question 76

The simple pitot tube does not measure the static pressure. dynamic pressure. velocity at the stagnation point. all (a), (b) and (c).

Answer 76

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

Question 77

Boundary layer separation occurs when the

Answer 77

cross-section of the channel is reduced.

Question 78

The head loss in turbulent flow in a pipe varies

Answer 78

approximately as the square of the velocity.