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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
601.

Stanton diagram is a plot of

A. friction factor against log of Reynold number
B. 1.25
C. log of friction factor against Reynold number
D. log of driction factor against log of Reynold number
E. friction factor against Reynold number
Answer» D. log of driction factor against log of Reynold number
602.

Select the quantity in the following that is not a dimensionless parameter

A. Kinematic viscosity
B. Darcy weisbach friction factor
C. Weber number
D. Froude number
E. Pressure coefficient
Answer» A. Kinematic viscosity
603.

Four cars, with a mass of 1500 kg each, are loaded on a 6 m wide, 12 m long small car ferry. How far, in cm, will it sink in the water?

A. 8.3
B. 11.5
C. 10.2
D. 15.2
E. 9.6
Answer» A. 8.3
604.

By the usual gravity analysis as per B.I.S., the permissible tensile stresses at the upstream face of the dam under earthquake loading, should not exceed

A. Zero
B. 100 kg/ cm2
C. 50 kg/ cm2
D. 150 kg/ cm2
E. 200 kg/ cm2
Answer» A. Zero
605.

In laminar flow

A. The viscosity is unimportant
B. The fluid particles move in irregular and haphazard paths
C. Is fixed in space in steady flow
D. Experimentation is required for the sirmplest flow cases
E. Newton's law of viscosity applies
Answer» E. Newton's law of viscosity applies
606.

Uniform flow occurs when

A. Conditions do not change with time at any point
B. Rate of change of velocity of fluid is zero
C. At every point the velocity vector is identical in magnitude and direction for any given instant
D. The change in transverse direction are zero
E. None of the above
Answer» C. At every point the velocity vector is identical in magnitude and direction for any given instant
607.

The depth of water in a 3 m wide rectangular, finished concrete channel is 2m. If the slope is 0.001, estimate the flow rate, in m3/s

A. 14
B. 12
C. 11
D. 13
E. 10
Answer» A. 14
608.

A small plastic boat loaded with pieces of steel rods is floating in a bath tub. It the cargo is dumped into the water allowing the boat to float empty, the water level in the tub will

A. Fall
B. Fall and then rise
C. Rise and then fall
D. Not change
E. Rise
Answer» A. Fall
609.

The velocity in a 2 cm-diameter pipe is 20 m/s. If the pipe enlarges to 5 cm diameter velocity, in m/s, will be

A. 6.4
B. 5.2
C. 3.2
D. 4.8
E. 8
Answer» C. 3.2
610.

For hydrodynamically rough boundary the friction coefficient

A. Depends on velocity and relative roughness
B. Varies with Reynold's number
C. Depends on Reynolds number, pressure gradient and relative roughness
D. Remains constant
E. Depends on relative roughness
Answer» E. Depends on relative roughness
611.

In turbulent flow

A. Cohesion is more effective than momentum transfer in causing shear stress
B. Momentum transfer is on a molecular scale only
C. One lamina of fluid flides smoothly over another
D. Shear stresses are generally larger than in similar laminar flow
E. The fluid particles move in an orderly manner
Answer» D. Shear stresses are generally larger than in similar laminar flow
612.

If a barometer carries wter instead of mercury, the height of column for a pressure equivalent to 75 cm of mercury will be

A. 1034 cm
B. 1040 cm
C. 1000 cm
D. 1050 cm
E. 1020 cm
Answer» E. 1020 cm
613.

In which of the following case of modelling, Reynold number will be used for studying?

A. Hydraulic jump
B. Flow configuration of harbours
C. Flow of castor oil through pipes
D. All of the above
Answer» C. Flow of castor oil through pipes
614.

A hydro-electric site has a head of 100 m and an average discharge of 10m3/s. Assume 92% efficiency, for a greater speed of 6000 rpm, the specific speed of turbine would be

A. 600
B. 1000
C. 1500
D. 1900
E. None of the above
Answer» A. 600
615.

The units of kinematic viscosity are

A. kg/m2-sec
B. kg sec/m2
C. m kg/sec.
D. m2/sec
E. m/kg sec
Answer» D. m2/sec
616.

Bluff body

A. Surface is smooth so that friction can be neglected
B. Surface does not coincide with stream lines
C. Surface perpendicular to stream lines
D. 8.3
E. Surface coincides with stream lines
Answer» B. Surface does not coincide with stream lines
617.

The horizontal component of force on a curved surface is equal to the

A. Scalar sum of all elemented horizontal components
B. Product of pressure at its centroid and area
C. Weight of liquid retained by the curved surface
D. Weight of liquid vertically above the curved surface
E. Force on a projection of the curved surface into a vertical plane
Answer» E. Force on a projection of the curved surface into a vertical plane
618.

Froude number is useful in calculations for

A. Hydraulic jump
B. Surface tension force
C. Flow through pipes
D. Compressible flow problems
E. Water hammer
Answer» A. Hydraulic jump
619.

Manning's formula is used to determine

A. Friction head loss in irregular sections
B. Discharge through weirs and notches
C. Friction head loss in open channels
D. Friction hed loss in pipes running full
E. Friction head loss in pipes running partially full
Answer» C. Friction head loss in open channels
620.

A 2 cm dia. Pipe transports water at 20 m/s. If it exits out 100 small 2 mm dia. Holes, the existing velocity, in m/s will be

A. 80
B. 40
C. 120
D. 10
E. 20
Answer» E. 20
621.

The angle of contact (0) between water and glass tube in case of capillary rise is equal to

A. 90?
B. 128?
C. 10?
D. 157?
E. 0?
Answer» E. 0?
622.

In case the velocity vector at different points along a stream line remains unchanged then the flow is termed as

A. Irrotational flow
B. Uniform flow
C. Stoke's flow
E. Rotational flow
Answer» B. Uniform flow
623.

The depth of oil having specific gravity 0.6 to produce a pressure of 3.6 kg/cm2 will be

A. 36 m of oil
B. 50 m of oil
C. 60 m of oil
D. 40 m of oil
E. 120 m of oil
Answer» C. 60 m of oil
624.

A flow in which each liquid particle has a definite path and their paths do not cross each other is called

A. Steady flow
B. Uniform flow
C. Stream line flow
D. Turbulent flow
E. None of the above
Answer» C. Stream line flow
625.

The losses in an open channel vary

A. Inversely as the hydraulic radius
B. As the velocity
C. Inversely with a gradient
D. As the square of velocity
E. As the cube of velocity
Answer» D. As the square of velocity
626.

The existence of velocity potential in fluid indicates that

A. the flow is rotational
B. the vorticity must be non-zero
C. the circulation around any closed curve must have a definite value
E. the vorticity must be zero
Answer» E. the vorticity must be zero
627.

Pressure drag results from

A. 10
B. Deformation drag
C. development
D. Skin friction
E. Occurrence of a wake
Answer» E. Occurrence of a wake
628.

Density in terms of viscosity is

A. Kinematic viscosity/Dynamic viscosity
B. Dynamic viscosity/Kinematic viscosity
C. Kinematic viscosity x dynamic viscosity
D. Any of the above
E. None of the above
Answer» B. Dynamic viscosity/Kinematic viscosity
629.

In axial flow turbines

A. Water enters radially but leaves axially
B. Water enters axially but leaves radially
C. Water enters at an angle but leaves axially
D. Water enters axially and leaves axially
E. None of the above
Answer» D. Water enters axially and leaves axially
630.

A low pressure of the order of 10-10 torr is to be measured in a chamber. Which of the following device can be used for this?

A. McLeod gauge
B. Pirani gauge
C. Manometer
D. Bourdon vacuum gauge
E. Ionisation chamber
Answer» E. Ionisation chamber
631.

When the dynamic viscosity of a fluid is 0.6 poise and specific gravity is 0.6, the kinematic viscosity of that fluid will be

A. 0.36 poise
B. 0.6 poise
C. 1 poise
D. None of the above
E. More than 20?
Answer» C. 1 poise
632.

The centre of pressure of a fully submerged body is almost always located

B. above the centroid
C. at the centroid
D. closer to the centroid
E. bolow the centroid
Answer» C. at the centroid
633.

If 1% error is encountered in the measurement of head over crest of a rectangular weir, the error in discharge will be nearly

A. 5%
B. 1%
C. 2%
E. 1.50%
Answer» E. 1.50%
634.

A hot wire anemometer is used for the measurement of

A. Viscosity of liquids
B. Viscosity of gases
C. Pressure of gases
D. Density of liquids
E. Velocity of gases
Answer» E. Velocity of gases
635.

Koyna dam is located in

A. Gujrat
B. Maharashtra
C. Rajasthan
D. Madhya Pradesh
E. Karnataka
Answer» B. Maharashtra
636.

Spouting velocity is

A. Ideal velocity of jet
B. 50% of ideal velocity of jet
C. Actual velocity of jet
D. Velocity of jet under some specified conditions
E. None of the above
Answer» A. Ideal velocity of jet
637.

A concrete masonry block on a hill side for supporting and fixing the penstock is known as

A. Anchor block
B. Support block
C. Concrete block
D. Base block
E. Any of the above
Answer» A. Anchor block
638.

The capillary rise in a narrow two-dimensional slit of width 'W' is

B. helf of that in a capillary tube of diameter 'W'
C. two-thirds of that in a capillary tube of diameter 'W'
D. One-third of that in a capillary tube of diameter 'W'
E. One-fourth of that in a capillary tube of diameter 'W'
Answer» B. helf of that in a capillary tube of diameter 'W'
639.

The wake

A. always occurs after a separation point
B. is a region of high pressure intensity
C. always occurs before and after separation point.
D. always occurs before a separation point
Answer» A. always occurs after a separation point
640.

At point A in a pipe line carrying water the diameter is 1 m, the pressure 98 kPa and the velocity 1 m/s. At point B, 2 m higher than A, the diameter is 0.5 m and the pressure 20 kPa. The direction of flow would be

A. A to B
B. B to A
C. Cannot be ascertained from data
E. None of the above
Answer» A. A to B
641.

In which contact condition case the value of coefficient of friction is expected to be highest?

A. Steel on steel
B. Steel on steel with two layers of graphite service in between
C. Steel on concrete
D. Steel on steel, greased plates
E. Packing and liner
Answer» C. Steel on concrete
642.

Stanton diagram is a plot of

A. log of friction factor against log of Reynolds number
B. friction factor against Reynolds number
C. friction factor against log of Reynolds number
E. log of friction factor against Reynolds number
Answer» A. log of friction factor against log of Reynolds number
643.

A body floats in stable equilibrium

A. When the C.G. of body is below the centre of buoyancy
B. When the metacentre is below C.G.
C. When the C.G. of body is above the surface of water
D. When the metacentric height is zero
E. When the metacentre is above C.G.
Answer» E. When the metacentre is above C.G.
644.

Which two forces are most important in floating bodies

A. Viscous, buoyancy
B. Gravity, inertial
C. Pressure, viscous
D. Buoyancy, gravity
E. Inertial, pressure
Answer» D. Buoyancy, gravity
645.

Capillarity is due to

A. Adhesion
B. Adhesion and cohesion
C. Gravity
D. Cohesion
E. Molecular structure
Answer» B. Adhesion and cohesion
646.

Capillary action is due to the

A. Viscosity of liquid
B. Cohesion of liquid particles
C. Surface tension
D. Adhesion of liquid particles on the surface
E. None of the above
Answer» C. Surface tension
647.

Capacity of a hydro-electric plant in service in excess of the peak load is known as

A. Peak reserve
B. Hot reserve
C. Spinning reserve
D. Cold reserve
E. Operating reserve
Answer» E. Operating reserve
648.

Mach number is significant in

A. Flow in space above the atmosphere of air
B. High speed flow of water
C. Flow of highly viscous fluids
D. Flow of metallic fluids
E. Flow in air at speeds more than that of sound
Answer» E. Flow in air at speeds more than that of sound
649.

Critical speed of turbine is

A. Same as maximum operating speed
B. Same as run away speed
C. The speed equal to synchronous speed of generator
D. The speed at which shaft will break
E. The speed at which the number of natural vibrations or natural frequency equals the number of revolutions per minute
Answer» E. The speed at which the number of natural vibrations or natural frequency equals the number of revolutions per minute
650.

The disadvantage of burried penstocks is

A. Protection against freezing of conveyed water
B. Protection against earthquake shock
C. Difficulty in repair and maintenance
D. Immunity against rock sides, avalanches and falling tree
E. Protection against effect of temperature because of soil cover
Answer» C. Difficulty in repair and maintenance

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