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730+ Fluid Mechanics and Hydraulic Machines Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Civil Engineering , Mechanical Engineering .

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More MCQs
451.

The upper critical Reynolds number is

A. Important from a design view point
B. Not more than 2000
C. The number at which turbulent flow changes to laminar flow
D. About 2000
E. Of no practical importance in pipe flow problems
Answer» D. About 2000
452.

Abnormal load on a earth dam is

A. Weight of dam and structure above it
B. Water pressure corresponding to full reservoir level
C. Weight of the dam
D. Uplift
E. Wave pressure
Answer» E. Wave pressure
453.

In a Buttress dam the inclination of the deck with horizontal is kept between

A. 25? to 30?
B. 35? to 40?
C. 15? to 20?
D. 60? to 75?
E. 10? to 15?
Answer» B. 35? to 40?
454.

In which of the following types of flow the losses are maximum?

A. Turbulent flow
B. Critical flow
C. Transition flow
E. Laminar flow
Answer» A. Turbulent flow
455.

Which type of pump is different from others?

A. Lobe pump
B. Gear pump
C. Fuel pump for diesel engine
D. Sliding vane pump
E. Centrifugal pump
Answer» C. Fuel pump for diesel engine
456.

The velocity of a fluid particle at the centre of the pipe section is

A. Maximum
B. Minimum
C. Average
D. r.m.s.
E. Logarithmic average.
Answer» A. Maximum
457.

The turbine that cannot be installed in high head plant is

A. Kaplan turbine
B. Francis turbine, vertical
C. Francis turbine, horizontal
D. Pelton wheel, horizontal
E. Pelton wheel, vertical
Answer» A. Kaplan turbine
458.

Geometric similarity between model and prototype means

A. The similarity of linear dimensions
B. The similarity of motion
C. The similarity of forces
D. Vitrified clay.
E. The similarity of discharge
Answer» A. The similarity of linear dimensions
459.

The Reyonlds number may be defined as the ratio of

A. Viscous forces to inertial forces
B. Elastic forces to pressure forces
C. Viscous forces to gravity forces
D. Gravity forces to inertial forces
E. None of the above
Answer» E. None of the above
460.

The maximum velocity through a circular channel takes place when the depth of flow is equal to

A. 0.95 times the diameter
B. 0.25 times the diameter
C. 0.50 times the diameter
D. 0.37 times the diameter
E. 0.81 times the diameter
Answer» E. 0.81 times the diameter
461.

In a flow between two stationary parallel plates the shear stress is zero at

A. the top
B. at the centre where velocity is maximum
C. both at the base and at the top
E. the base
Answer» B. at the centre where velocity is maximum
462.

The head loss in turbulent flow in a pipe

A. Varies approximately as square of velocity
B. Varies conversely as square of velocity
C. Varies directly as velocity
D. Varies conversely with diameter
E. Varies inversely with diameter
Answer» A. Varies approximately as square of velocity
463.

A high speed vehicle, travelling at 50 m/s, dips an 80 cm wide scoop into water and deflects the water 180. If it dips 5 cm deep what force, in kN, is exerted on the scoop?

A. 200
B. 25
C. 120
D. 100
E. 50
Answer» A. 200
464.

A most economical channel section is one which for a given cross-section area

A. Has maximum depth of fluid flowing
B. Has maximum discharge
C. Has maximum hydraulic radius
D. Has maximum wetted perimeter
E. Has maximum velocity of fluid
Answer» B. Has maximum discharge
465.

Navier-stokes equation is useful in the analysis of

A. Viscous flow
B. Non-viscous flow
C. Rotational flow
D. Turbulent flow
E. Any of the above
Answer» A. Viscous flow
466.

Which one is different from the others?

A. Warped vane impeller
B. Shrouded impeller
C. Axial flow impeller
D. Mixed flow impeller
E. Open impeller
Answer» B. Shrouded impeller
467.

The ratio of average velocity to mzximum velocity for steady laminar flow in circular pipes is

A. ?
B. 2
C. 1
Answer» A. ?
468.

The metacentric height of ocean going vessels is usually of the order of

A. 1.8 m to 2.0 m
B. 30 cm to 1.2 m
C. 5 m to 7 m
D. 3 m to 5 m
E. 8 m to 10 m
Answer» B. 30 cm to 1.2 m
469.

A stepped notch is

A. A notch of varying shapes along the line of flow
B. A combination of triangular notches of different sizes
C. A combination of rectangular notches of different sizes
D. Semi-elliptical in section
E. A combination of triangular and a circular section
Answer» C. A combination of rectangular notches of different sizes
470.

A perfect gas

A. Has zero viscosity
B. Has constant viscosity
C. Satisfies the relation PV = mRT
D. Is incompressible
E. None of the above
Answer» C. Satisfies the relation PV = mRT
471.

A piece of cork weighing 4 kg floats in water with 40% of its volume under the liquid. Determine specific gravity of cork.

A. 1
B. 0.16
C. 0.4
D. 0.6
E. None of the above
Answer» C. 0.4
472.

A rotameter is a device used to measure

A. Vortex flow
B. Velocity of gauges
C. Density of fluids
D. Velocity of fluid in pipes
E. Flow of fluids
Answer» E. Flow of fluids
473.

If the specific speed of a pump is in the range 170 to 400, the type of pump would be

A. Axial flow
B. Radial flow
C. Mixed flow
D. Turbine type
E. None of the above
Answer» A. Axial flow
474.

A syphon is used to

A. To fill water from a reservoir at lower level to another reservoir with the help of a pump
B. To connect two reservoirs
C. To disconnect water from one reservoir to another
D. To connect two water reservoirs at different levels intervened by a mountain
E. To distribute water from a reservoir at higher level to reservoirs at lower levels
Answer» D. To connect two water reservoirs at different levels intervened by a mountain
475.

A circular plate 1 m in diameter submerged vertically in water such that its upper edge is 8 m below the free surface of water. The total hydrostatic pressure force on one side of the plate is

A. 65.4 kN
B. 45.0 kN
C. 6.7 kN
D. expands until it fills its space
E. 77.0 kN
Answer» C. 6.7 kN
476.

The falling drops of rain acquire spherical shape on account of

A. Surface tension
B. Buoyancy
C. Compressibility
D. Viscosity
E. Vapour pressure
Answer» A. Surface tension
477.

A foot valve is provided on

A. Centrifugal pumps
B. Kaplan turbines
C. Pelton wheels
D. High pressure devices
E. All of the above
Answer» A. Centrifugal pumps
478.

If the specific speed of a pump is calculated as 5000, the type of pump that should be selected is

A. Axial flow or propeller pump
B. Mixed flow or screw pump
C. Slow speed radial flow
D. Medium speed radial flow
E. High speed radial flow
Answer» A. Axial flow or propeller pump
479.

Newton's law of viscosity relates

A. Shear stress, temperature, viscosity and velocity
B. Pressure, vicosity and rate of angular deformation
C. Yield shear stress, rate of angular deformation and viscosity
D. Pressure, velocity and viscosity
E. Shear stress and rate of angular deformation in a fluid
Answer» E. Shear stress and rate of angular deformation in a fluid
480.

The length of mercury column at a place at an altitude will vary with respect to that at ground in a

A. Parabolic relation
B. First slowly and then steeply
C. Hyperbolic relation
D. Will remain constant
E. Linear relation
Answer» B. First slowly and then steeply
481.

Which of the following forces does not act in case of fluids?

A. Gravity force
B. Elastic force
C. Vibratory force
D. Centrifugal force
E. Tensile force
Answer» E. Tensile force
482.

A stream line

A. Is the line along the geometrical centre of the flow
B. Is the line of equal velocity in a flow
C. Occurs in all types of flow
D. Is the line along which the rate of pressure drop is uniform
E. Is fixed in space in steady flow
Answer» E. Is fixed in space in steady flow
483.

A surge wave is an example of

A. 10
B. steady uniform flow
C. unsteady non-uniform flow
D. steady non-uniform flow
E. unsteady uniform flow
Answer» C. unsteady non-uniform flow
484.

Find the odd one out

A. Modulus of elasticity
B. 51.3
C. Unit shear stress
D. Pressure
E. Energy
Answer» E. Energy
485.

Atmospheric pressure held in terms of water column is

A. 7.5 m
B. 8.5 m
C. 9.81 m
D. 10.30 m
E. None of the above
Answer» D. 10.30 m
486.

The arch dam is not suitable for

A. Low heads
B. Small discharge
C. Wider sites
D. Narrow sites
E. Small discharge and low heads
Answer» C. Wider sites
487.

What pressure, in kPa, is equivalent to 600 mm of Hg?

A. 51.3
B. 100
C. 80
D. 55.2
E. 95.2
Answer» C. 80
488.

Which two forces are most important in laminar flow between closely spaced parallel plates

A. Inertial, viscous
B. Pressure, inertial, inetial
C. Gravity, pressure
D. Viscous, pressure
E. None of the above
Answer» A. Inertial, viscous
489.

The velocity of flow through homogeneous porous media under constant head is

A. directly proportional to the coefficient of permeability
B. inversely proportional to the coefficient of permeability
D. inversely proportional to the square of the coefficient of permeability
E. directly proportional to the square of the coefficient of permeability
Answer» E. directly proportional to the square of the coefficient of permeability
490.

It is desired to predict the performance of a large centrifugal pump from that of a scale model one fourth the diameter. The model absorbs 20 HP when pumping under test head of 20 m at its best speed of 400 r.p.m. The large pump is required to pump against 60 m head. The following will be the speed of the pump

A. 173 RPM
B. 153 RPM
C. 208 RPM
D. 100 RPM
E. 167 RPM
Answer» A. 173 RPM
491.

The angle of taper on a draft tube is

A. More than 15?
B. Around 10?
C. Less than 7
D. More than 20?
E. Around 15?
Answer» C. Less than 7
492.

To determine the reservoir storage capacity for a given uniform demand, one of the following data is most useful

A. Daily flow-duration curve of the stream at the dam site
B. 1.25
C. Stage discharge relation for the stream at the reservoir site
D. Mass curve of the flow volume for several consecutive years
E. Unit hydrograph of the basin
Answer» D. Mass curve of the flow volume for several consecutive years
493.

If the Mach number of a flow is 3 the flow is known as

A. Super-supersonic
B. Supersonic
C. Sonic
D. Sub-sonic
E. None of the above
Answer» B. Supersonic
494.

Select the correct statement regarding frictionless flow

A. The velocity is always sonic at the throat of a converging diverging tube
B. In diverging conduits the velocity always decreases
C. On supersonic flow the area decreases for increasing velocity
D. Sonic velocity cannot be exceeded at the throat of a converging diverging tube
E. Less than 3 m of water
Answer» C. On supersonic flow the area decreases for increasing velocity
495.

Pascal's law states that pressure at a point is equal in all directions

A. In a liquid at rest
B. In a fluid at rest
C. In a laminar flow
D. In a turbulent flow
E. None of the above
Answer» B. In a fluid at rest
496.

A practical example of steady non-uniform flow is given as the

A. Flow through venturimeter
B. Motion of a river around the pillars of a bridge
C. Constant discharge through straight tapering draft tube turbine
D. Flow through delivery pipe of a reciprocating pump
E. Steadily decreasing flow through a reducing section
Answer» C. Constant discharge through straight tapering draft tube turbine
497.

If a centrifugal pump takes too much power, the cause may be

A. Air in water
B. Foot valve too small
C. Air leakage
D. Low speed
E. Heavy liquid.
Answer» E. Heavy liquid.
498.

Out ward radial flow turbines

A. Are impulse type
B. Are reaction type
C. Are partly impulse partly reaction
D. May be impulse or reaction type
E. None of the above
Answer» D. May be impulse or reaction type
499.

The statement "For laminar flow through a fine porous bed or capillary passages in a solid, the velocity based on the total cross-section is proportional to the ratio of pressure gradient to viscosity" is known as

A. Schmidt's law
B. Fick's law
C. Reynolds hypothesis
D. Stock's law
E. Darcy's law of permeability
Answer» E. Darcy's law of permeability
500.

Cavitation is caused by

A. Low velocity
B. Low pressure
C. High velocity
D. Low barometric pressure
E. High pressure
Answer» B. Low pressure

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