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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
351.

The lowest portion of storage basin from where the water is not drawn usually, is

A. Reserve storage
B. Dead storage
C. Bottom storage
D. Spring reserve
E. Sub-soil storage
Answer» B. Dead storage
352.

If the specific speed of a turbine is 800 the turbine should be

A. Kaplan
B. Pelton wheel
C. Girard
D. Fourneyron
E. Francis
Answer» A. Kaplan
353.

Relative velocity is

A. Sum of two velocities
B. Average velocity
C. The difference between two velocities
D. Vector difference of two velocities
E. The difference between the higher velocity and average velocity
Answer» D. Vector difference of two velocities
354.

As the temperature decreases, the viscosity of a gas

A. 2.45
B. increases, increases
C. decreases, decreases
D. increases, decreases
E. decreases, increases
Answer» E. decreases, increases
355.

The horizontal to vertical side slope in case of Cpppoletti weir is

A. I : I
B. 1 : ?2
C. I : 4
D. 4 : I
E. I : 2
Answer» C. I : 4
356.

In case of Constant Angle Arch Dam, the most favourable central angle is

A. 170?
B. 90?
C. 165?
D. 133?
E. 73?
Answer» D. 133?
357.

A trapezoidal weir of horizontal crest with side slopes of one horizontal to four vertical is called

A. trapezoidal weir
B. cippoletti weir
C. sultro weir
D. None of the above
Answer» B. cippoletti weir
358.

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

B. Gravity and pressure
C. Viscous and pressure
D. Inertial and viscous
E. Pressure and inertial
Answer» C. Viscous and pressure
359.

SI unit of viscosity is

A. 10 times poise
B. 9.81 times poise
C. 1/9.81 times poise
D. Equal to poise
E. None of the above
Answer» A. 10 times poise
360.

If the specific speed of turbine is more than 300, the type of turbine is

A. Kaplan
B. Pelton with nose jets
C. Greater than ten
D. Pelton
E. Francis
Answer» A. Kaplan
361.

The velocity distribution in a turbulent flow in a pipe is often assumed to

A. be zero at the wall and increase linearly to the centre
B. vary according to the 1/7 th power law
C. be maximum at the wall and decrease linearly to the centre
D. be unpredictable and is thus not used
E. vary parabolically
Answer» B. vary according to the 1/7 th power law
362.

Which conduit entrance is expected to have highest loss coefficient?

A. Gate in thin wall-unsuppressed contraction
B. Fully rounded entrance having x/D>0.15
C. Gate in thin wall-bottom and side suppressed
D. Inward projecting entrances
E. Gate in thin wall-corners rounded
Answer» A. Gate in thin wall-unsuppressed contraction
363.

The principle, "The buoyancy is equal to the weight of the fluid displaced and the line of action is through the centroid of the displaced mass" is known as

A. Newton's law
B. Bernoulli's law
C. First law of fluid mechanics
D. Law of buoyancy
E. Archimedes principle
Answer» E. Archimedes principle
364.

Predict the pressure, in kPa, at an elevation of 2000 m, in an isothermal atmosphere assuming T = 20?C. Assume Patm = 100 kPa

A. 71
B. 79
C. 87
D. 82
E. 63
Answer» B. 79
365.

The distance from pipe boundary, at which the point velocity is equal to average velocity in case of turbulent flow (when R is the radius of the pipe), is

A. 0.892 R
B. 0.223 R
D. 0.446 R
E. 0.111 R
Answer» B. 0.223 R
366.

A fluid in which resistance to deformation is independent of the shear stress is known as

A. Bingham plastic fluid
B. Pseudo plastic fluid
C. Dilatant fluid
D. Newtonian fluid
E. None of the above
Answer» D. Newtonian fluid
367.

The minimum diameter necessary to avoid the capillary rise in the manometer is

A. 6 mm
C. 1 mm
D. 3 mm
E. 15 mm
Answer» A. 6 mm
368.

Which of the following forces do not act on fluids

A. Gravity
B. Viscous force
C. Torsion
D. Inertia
E. Pressure
Answer» C. Torsion
369.

In a centrifugal pump casing, the flow of water leaving the impeller is

A. Radial flow
B. Forced vortex motion
C. Centrifugal flow
D. Free vortex motion
E. Rectilinear flow
Answer» D. Free vortex motion
370.

Fresh water 2 m deep flows over the top of 4 m of salt water (S = 1.04). The pressure at the bottom, in kPa, is

A. 60.4
B. 58.8
C. 55.2
D. 51.3
E. 47.9
Answer» A. 60.4
371.

Hydraulic jump is used for

A. Reducing the velocity of flow
B. Reducing the energy of flow
C. Increasing the flow rate
D. Reducing the flow rate
E. Reducing turbulence
Answer» B. Reducing the energy of flow
372.

When the rheogram for a fluid at any temperature and pressure is a straight line passing through origin, the fluid is said to be

B. Newtonian
C. Non-Newtonian
D. Bingham
E. Ideal plastic
Answer» B. Newtonian
373.

The miaimum thickness of boundary layer in a pipe of radius R is

A. 0.22 R
B. R
D. 0.5 R
E. 0.1 R
Answer» B. R
374.

The hydrostatic law states that rate of increase of pressure in a vertical direction is equal to

A. Density of the fluid
B. Specific weight of the fluid
C. Weight of the fluid
D. None of the above
E. Is practically incompressible
Answer» B. Specific weight of the fluid
375.

In open channels, under critical flow conditions, the velocity head is equal to

A. one-fourth the depth of flow
B. the depth of flow
C. two-thirds of the depth of flow
E. half the depth of flow
Answer» E. half the depth of flow
376.

Which of the following pumping device for supplying water to boiler does not have moving parts?

A. Multistage centrifugal pump
B. Duplex pump
C. Simplex pump
D. Single stage centrifugal pump
E. Steam injector
Answer» E. Steam injector
377.

Which one of the following is laminar flow

A. Rise of water in plants through roots
B. Movement of blood in the arteries of a human body
C. Flow of oil in measuring instruments
D. All of the above
E. None of the above
Answer» D. All of the above
378.

A simple pitot tube is used to measure

A. The total pressure
B. The undistributed fluid pressure
C. The pressure in a static fluid
D. The velocity in a flowing stream
E. The dynamic pressure
Answer» D. The velocity in a flowing stream
379.

The wake

A. Always occurs after a separation point
B. Is the principal cause of skin friction
C. Always occurs when deformation drag predominates
D. Is none of these answers
E. Is a region of high pressure
Answer» C. Always occurs when deformation drag predominates
380.

For safety against overturning in a gravity dam, the resultant of all the forces acting on a dam must pass

A. Middle third of the base
B. Outside the base
C. Just at extreme edge of the base
D. First third of the base
E. Within 10% of the extreme edge
Answer» A. Middle third of the base
381.

A current meter is used for the measurement of

A. Electrical charge on fluids
B. Velocity
C. Electrical conductivity
D. Pressure
E. Viscosity
Answer» B. Velocity
382.

Rocks that undergo notable expansion without flow due to preence of clay minerals, are known as

A. Swelling rocks
B. Moderately jointed rocks
C. Seamy rocks
D. Schistos rocks
E. Squeezing rocks
Answer» A. Swelling rocks
383.

Which one of the following is an integrator

A. Bus-bar
B. Exciter
C. Transformer
D. Lightning arrestor
E. Oil circuit breaker
Answer» B. Exciter
384.

In a Buttress dam, when the height of dam is 10 m to 25 m, the spacing of buttress is usually restricted to

A. 10 to 15 m
B. 4.5 to 6 m
C. 20 to 25 m.
D. 1.5 m
E. 1 m
Answer» B. 4.5 to 6 m
385.

A mercury water manometer indicates a gauge difference of 400 mm. The difference in pressure, measured in metres of water, is

A. 0.4
B. 0.8
C. 1088
D. 5.44
E. None of the above
Answer» D. 5.44
386.

The equation of continuity of flow is applicable when

A. The flow is one dimensional
B. The flow is steady
C. The flow is compressive
D. The velocity is uniform over the cross section
E. None of the above
Answer» E. None of the above
387.

A turbine model test with 260 mm diameter showed an efficiency of 90 percent. The efficiency that can be expected from a 1.2 m diameter impeller is

A. 90 percent
B. 81 percent
C. 91 percent
D. 93.18 percent
E. None of the above
Answer» D. 93.18 percent
388.

Notch is a device used for measuring

B. Velocity through a pipe
C. Rate of flow through a small channel
D. Velocity through a small channel
E. Rate of flow through pipes
Answer» C. Rate of flow through a small channel
389.

While calculating the specific speed of double suction pump, the discharge to be considered is

A. Square of the actual discharge
B. Actual discharge
C. Double of the actual discharge
D. Square root of actual discharge
E. Half of actual discharge
Answer» E. Half of actual discharge
390.

In an impulse turbine

A. Water must be admitted over the whole circumference
B. It is not possible to regulate the flow without loss
C. Wheel must run full and kept entirely submerged in water below the tailrace
D. The pressure in the driving fluid as it moves over the vanes is atmospheric
E. None of the above
Answer» D. The pressure in the driving fluid as it moves over the vanes is atmospheric
391.

The Weber number is the ratio of

A. Inertial forces to surface tension force
B. Elastic forces to pressure forces
C. Viscous forces to gravity
D. Elastic forces to gravity
E. Intertial forces to viscous forces
Answer» A. Inertial forces to surface tension force
392.

A hydraulic jump is classified on the basis of initial

A. Weber number
B. Froude number
C. Mach number
D. Reynolds number
Answer» B. Froude number
393.

Water hammer in pipes takes place when

A. 51.3
B. flowing fluid is gradually brought to rest
C. fluid is flowing with high pressure
D. fluid is flowing with high velocity
E. flowing fluid is suddenly brought to rest by closing the valve
Answer» B. flowing fluid is gradually brought to rest
394.

Multistage centrifugal pumps are used

A. To produce high heads
B. To give high discharge
C. A and B above together
D. To pump viscous liquids
E. None of the above
Answer» A. To produce high heads
395.

When the water flows over a rectangular suppressed weir the pressure beneath the nappe is

A. Atmospheric
B. Slightly above atmospheric
C. Vacuum
D. Very high
E. Negative
Answer» E. Negative
396.

Water flows through a 2 cm dia. Pipe at 20 m/s. It then flows radially outward between two discs, 2 mm apart. When it reaches a radius of 40 cm its velocity, in m/s will be

A. 1.85
B. 2.5
C. 1.25
D. 5
E. 2.25
Answer» C. 1.25
397.

Stremlines, streak lines and path lines are all identical in case of

A. Steady flow
B. Rotation flow
C. Non-uniform flow
D. Uniform flow
E. Unsteady flow
Answer» A. Steady flow
398.

An equipotential line

A. Exists in case of rotational flow
B. Has uniformly varying dynamic pressure
C. Has no velocity component tangent to it
D. Exists in case of turbulent flow only
E. Has no velocity component normal to it
Answer» C. Has no velocity component tangent to it
399.

The unit hydrograph may be obtained by dividing the ordinates of the direct run-off hydrograph of a storm by

A. total run off volume
B. duration of unit hydrograph
D. storm duration
E. direct run-off volume
Answer» E. direct run-off volume
400.

The stress in the dam should be within the specified limits for the body of dam in the foundations. If the stress at the toe and heel are excessive, they can be brought within permissible limits by

A. Grouting
B. Providing anchor blocks
C. Providing friction blocks
D. Providing filters
E. Any of the above
Answer» D. Providing filters

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