Fluid Mechanics for Chemical Quiz 3

1 / 50

Centre of pressure of a plane surface of arbitrary shape immersed vertically in a static mass of fluid_________?

Is independent of the specific weight of the fluid

Is different for different fluids

Is at the centroid of the plane surface

Lies above the centroid of the plane surface

2 / 50

Diaphragm pumps are used to transport__________?

Liquids

Slurries

Solids

Fluids

3 / 50

Buoyant force___________?

Depends on the depth of the submergence of the floating body

None of these

For non-symmetrical bodies is not vertical

Depends on the weight of the floating body

4 / 50

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) ?

FL-2T, ML-1T-1

ML-1T-3, F-1L2T

F-1L2T-1, MLT-3

FLT, ML-1T-1

5 / 50

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 ?

Data not sufficient to relate f1 & f2

f1 = f2

f1 > f2

f1 < f2

6 / 50

Capacity of a hydraulic accumulator is defined in terms of maximum_______?

Volume available in the cylinder

Rate of falling of ram

Amount of energy stored

Flow rate through accumulator

7 / 50

Cavitation occurs in a centrifugal pump when the suction pressure is_________?

Greater than the vapour pressure of the liquid at that temperature

Less than the vapour pressure of the liquid at that temperature

Equal to the developed head

Equal to the vapour pressure

8 / 50

Check valves are used________?

In bends

For unidirectional flow

At high pressure

For controlling water flow

9 / 50

Cp/Cv is termed as___________?

Adiabatic constant

Mach number

Prandtl number

Weber number

10 / 50

Disc compensators are provided in large diameter fuel gas carrying pipelines to__________?

Account for the pressure variation side the pipeline

Make the pipe joint leak-proof

Account for contraction/expansion of pipe due to temperature changes of the surroundings

Keep the pipe in proper orientation

11 / 50

Dimension of kinematic viscosity is_______?

MLT-1

L2T-2

L2T

L2T-1

12 / 50

Curve III in the bellow diagram represents a/an_________?

Dilatent fluid

Ideal plastic

None of these

Pseudo plastic fluid

13 / 50

Capillary tube method of viscosity measurement is based on the _________?

Stoke?s law

None of these

Hagen-Poiseuille?s equation

Navier-stokes equation

14 / 50

Deformation drag, which is caused by widespread deformation of fluid around the immersed body______?

Occurs when NRe is very small

Is independent of body length

Depends mainly on cross-sectional shape

Is primarily a friction drag

15 / 50

Boundary layer separation occurs when the______?

Velocity of sound is reached

Cross-section of the channel is reduced

Valve is closed in a pipeline

Pressure reaches a minimum

16 / 50

Diaphragm valves are used for handling ________ fluids?

Viscous

Non-Newtonian

Corrosive

Solid suspended

17 / 50

Colebrook equation for friction factor in turbulent flow is given by, f-0.5 = -4 loge [(?/D) + (1.26/NRe ?F). It reduces to Nikuradse equation for a value of (?/D) equal to ___________?

0.5

18 / 50

Check in a centrifugal pump is_________?

Provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running

Provided in the discharge line

All A., B. and C.

Generally a globe valve

19 / 50

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

d1/3

d2/3

20 / 50

Cd for the orifice plate varies from _____?

0.93 to 0.98

0.02 to 0.03

0.58 to 0.8

0.2 to 0.3

21 / 50

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

d4/5

d2/3

d1/3

22 / 50

Dean number is concerned with the______?

Psychrometry

Fluid flow through helical pipes

Power consumption in agitated vessels

Fluid-particle interaction

23 / 50

Design of the casing of centrifugal pump should be such as to minimise the_________?

Back flow through impeller

Loss of static head

Loss of kinetic head

None of these

24 / 50

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___________?

0.62

0.98

0.82

0.42

25 / 50

Check valve provided in the discharge line of a centrifugal pump serves the purpose of controlling the________?

All A., B. and C.

Discharge pressure

Back flow of fluid in the event of stoppage of pump

Flow of liquid during operation of the pump

26 / 50

Brownian movement is prominent in the particle size range of ______ microns in case of settling of a particle in a fluid?

0.01 to 0.10

2 to 3

200 to 300

100 to 1000

27 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Require less space

Have lower operating costs

Have quieter operation

All A., B. and C.

28 / 50

Cd is always _______ Cc?

Equal to

Greater than

Less than

Either more or less than

29 / 50

Centrifugal pump can?t be used to pump _______?

Thick molten soap at 80?C

None of the above

Moderately viscous vegetable oil used in soap industry

Molten sodium (used as a coolant in Fast Breeder Reactor)

30 / 50

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?

Head of the liquid pumped

BHP required by the pump

NPSH required

All A., B. and C.

31 / 50

Centre of pressure in an immersed body is _______ the centre of gravity?

Either above or below; depends on the liquid density

Below

Above

32 / 50

Choose the set of pressure intensities that are equivalent ?

4.33 psi, 10 ft. of water, 8.83 inches of Hg

10 psi, 19.7 ft. of water, 5.3 inches of Hg

10 psi, 19.7 ft. of water, 23.3 inches of Hg

4.33 psi, 10 ft. of water, 20.7 inches of Hg

33 / 50

Centrifugal pump is normally classified on the basis of the_________?

Type of casing

Impeller blade angle

rpm

Number of blades in impeller

34 / 50

Cocks are used to control _____?

Solids

Water

Any liquid

None of these

35 / 50

Cavitation in a centrifugal pump can be avoided by keeping the___________?

Inlet pressure low

Inlet pressure high

Outlet pressure low

Outlet pressure high

36 / 50

Differential manometer measures the______?

None of these

Atmospheric pressure

Sub-atmospheric pressure

Pressure difference between two points

37 / 50

Cavitation can be prevented by_________?

Maintaining suction head = developed head

Suitably designing the pump

Maintaining the suction head sufficiently greater than the vapour pressure

Maintaining suction head lower than the vapour pressure

38 / 50

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

F-2. L

F.L-2

FL-1

F-1. L

39 / 50

Differential manometer measures the_____?

Absolute pressure

Pressure difference

Gauge pressure

Pressure gradient

40 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

Can be run with discharge line valve closed for a short interval

Do not need priming

Run at a lower speed for the same discharge

Deliver fluid with pulsating/fluctuating discharge

41 / 50

Creeping flow around a sphere is defined, when particle Reynolds number is_____?

< 500

< 2100

> 2.5

< 0.1

42 / 50

Check valve is used for _________ flow?

Unidirectional

Very precise control of

None of these

Multidirectional

43 / 50

Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, ? = surface tension of mercury)______?

1/d

1/?

44 / 50

Critical velocity in a pipe flow__________?

Independent of fluid density

Increases as fluid viscosity increases

None of these

Increases as pipe diameter increases

45 / 50

Co-efficient of velocity is _____ the coefficient of discharge?

More than

Less than

Not related to

Equal to

46 / 50

Dimension of absolute viscosity is__________?

ML-1T-1

MLT

ML-1T

MLT-1

47 / 50

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

Develops high pressure

Develops noise

Increase in thrust

Decrease in effect

48 / 50

Buckingham-? theorem states that in any physical problem including ?n? quantities having ?m? dimensions, the quantities can be arranged into ______ independent dimensionless parameters?

n-m

n/m

49 / 50

Capacity of a rotary gear pump can be varied by___________?

Changing the speed of rotation

Bleeding air into suction

Bypassing liquid from the suction or discharge line

All A., B. and C.

50 / 50

Choking in case of pipe flow means that a_____?

Restriction in flow cross-section area occurs

Valve is closed in the line

Specified mass flow rate cannot be achieved

None of these

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