laboursonline – MCQs, Mock Tests | Engineering Civil Engineering -MCQS-Hydraulics Section 3

For exerting a pressure of 4.8 kg/cm2, the depth of oil (specific gravity 0.8), should be

1. 60 cm
2. 56 cm
3. 40 cm
4. 41 cm

✅ Correct Answer: 1

For the flow of liquid from an open ended tube (or nozzle) leading to the formation of spray of liquid drops, the number generally applied, is

1. Froude number
2. Weber number
3. Reynold number
4. Mach number.

✅ Correct Answer: 2

To avoid vapourisation, pipe lines are laid over the ridge so that these are above the hydraulic gradient line, not more than

1. 2.4 m
2. 6.4 m
3. 10.0 m
4. 5.0 m

✅ Correct Answer: 2

A jet projected at an angle of 45θ, 40 m from the foot of a vertical column, just reaches the top of the column. The height of the column is

1. 15 m
2. 20 m
3. 30 m
4. 40 m

✅ Correct Answer: 4

Atmospheric pressure varies with

1. altitude
2. temperature
3. weather conditions
4. all of the above.

✅ Correct Answer: 4

The magnitude of water hammer in a pipe depends upon

1. speed at which value is closed
2. length of the pipe line
3. elastic properties of the following liquid
4. all the above

✅ Correct Answer: 4

If velocities of fluid particles vary from point to point in magnitude and direction, as well as from instant to instant, the flow is said to be

1. laminar
2. turbulent flow
3. uniform flow
4. non-uniform flow.

✅ Correct Answer: 2

The rise of the liquid along the walls of a revolving cylinder above the initial level, is

1. greater than the depression of the liquid at the axis of rotation
2. lesser than the depression of the liquid at the axis of rotation
3. the same as the depression of the liquid at the axis of rotation
4. none of these.

✅ Correct Answer: 3

Fluids change the volume under external presssure due to

1. plasticity
2. viscosity
3. compressibility
4. none of these.

✅ Correct Answer: 3

Discharge over an ogee weir remains the same as that of

1. sharp crested weir
2. triangular weir
3. cippoletti weir
4. drowned weir.

✅ Correct Answer: 3

When no air is left below the nappe and water stream adheres to the down stream face of the weir, it is known as

1. free nappe
2. depressed nappe
3. clinging nappe
4. none of these.

✅ Correct Answer: 3

The best side slope for most economical trapezoidal section, is

1. 30°
2. 45°
3. 60°
4. none of these.

✅ Correct Answer: 3

The following is not a laminar flow

1. Flow of oil in measuring instruments
2. Flow in beds in ground water
3. Rise of water in plants through roots
4. Flow in water pipe lines.

✅ Correct Answer: 4

Which one of the following statements is true ?

1. The value of kinetic energy correction factor for turbulent flow lies between 1.03 to 1.06
2. The value of kinetic energy correction factor for laminar flow is 2
3. The practical value of kinetic energy correction factor for turbulent flow is unity
4. all the above.

✅ Correct Answer: 4

Uniform flow is said to occur when

1. size and shape of the cross-section in a particular length remain constant
2. size and shape of the cross-section change along a length
3. frictional loss in the particular length of the channel will the more than the drop in its elevation
4. frictional loss in the particular length of the channel, will be less than the drop in elevation.

✅ Correct Answer: 1

Molecules of fluids get attracted due to

1. capillarity action
2. surface tension
3. adhesion
4. cohesion

✅ Correct Answer: 3

Cappoletti weir is a

1. rectangular weir whose length is kept 3 times the height of the water above sill
2. triangular weir whose notch angle is 90°
3. trapezoidal weir, whose sides slope 1 horizontal to 2 verticals
4. a combination of rectangular and triangular weirs.

✅ Correct Answer: 3

On an inclined plane, centre of pressure is located

1. at the centroid
2. above the centroid
3. below the centroid
4. anywhere.

✅ Correct Answer: 3

Atmospheric pressure is equal to water column head of

1. 9.81 m
2. 5.0 m
3. 10.30 m
4. 7.5 m.

✅ Correct Answer: 3

Shear stress is directly proportional to

1. the velocity
2. the shear strain
3. the viscosity
4. the velocity.

✅ Correct Answer: 2

To avoid an interruption in the flow of a syphon, an air vessel is provided

1. at the inlet
2. at the outlet
3. at the summit
4. at any point between intet and outlet.

✅ Correct Answer: 3

Pick up the correct statement from the following :

1. Total energy gradient is the graphical representation of the total head at any section of a pipe line
2. Vertical distance between the total energy line and hydraulic grade line is equal to the velocity head
3. Vertical distance between the total energy line and total energy gradient represents loss of head
4. all the above.

✅ Correct Answer: 4

A fluid particle may possess the displacement of

1. translation
2. rotation
3. distortion
4. all the above.

✅ Correct Answer: 4

Pick up the correct statement from the following :

1. When the length of the tube is equal to diameter of the internal mouth piece, the jet of liquid comes out without touching the sides of the tube
2. When the length of the tube is three times the diameter of the internal mouth piece, the jet diameter is equal to diameter of the tube.
3. both (a) and (b)
4. Neither (a) nor (b).

✅ Correct Answer: 3

Piezometers are used to measure

1. pressure in water channels, pipes etc.
2. difference in pressure at two points
3. atmospheric pressure
4. very low pressure.

✅ Correct Answer: 4

Most economical section of a triangular channel, is

1. equilateral triangle
2. right angled triangle
3. isosceles triangle with 45° vertex angle
4. right angled triangle with equal sides.

✅ Correct Answer: 4

In an open tube, free surface of mercury remains

1. horizontal
2. curved upwards
3. curved downwards
4. none of these.

✅ Correct Answer: 3

Manometers are used to measure

1. pressure in water channels, pipes etc.
2. difference in pressure at two points
3. atmospheric pressure
4. very low pressure.

✅ Correct Answer: 1

For maximum horse power of a nozzle, the head supplied must be equal to

1. head loss in the pipe due to friction
2. twice the head loss in the pipe due to friction
3. thrice the head loss in the pipe due to friction
4. four times the head loss in the pipe due to friction.

✅ Correct Answer: 3

The ratio of frictional factor and coefficient of friction used in general equation for a head loss in a pipe, is A. 1

1. 1
2. 2
3. 3
4. 4

✅ Correct Answer: 4

Flow in pipes is turbulent if Reynold number is

1. less than 2100
2. more than 3000
3. between 2100 and 3000
4. none of these.

✅ Correct Answer: 2

Back water curve is caused if

1. friction head loss is more than the bed slope
2. pressure is due to weir in the channel
3. there is an increase in width of the channel
4. none of these.

✅ Correct Answer: 2

Power transmitted through a pipe is maximum when friction head loss, is

1. one-half of the total head supplied
2. one-third of the total head supplied
3. one-fouth of the total head supplied
4. equal to the total head supplied.

✅ Correct Answer: 2

The specific weight of water is 1000 kg/m3

1. at normal pressure of 760 mm
2. at 4°C temperature
3. at mean sea level
4. all the above.

✅ Correct Answer: 4

Specific weight of liquid

1. remains constant at every place
2. does not remain constant at every place
3. varies from place to place on the earth
4. does not vary on any other planet.

✅ Correct Answer: 4

Manning's formula is used for

1. flow in open channels
2. head loss due to friction in open channels
3. head loss due to friction in pipes flowing full
4. flow in pipes.

✅ Correct Answer: 2

A non-uniform steady flow is through

1. a long tube at a decreasing rate
2. an expanding tube at constant rate
3. an expanding tube at increasing rate
4. a long pipe at increasing rate.

✅ Correct Answer: 2

An ideal fluid is

1. incompressible
2. compressible
3. compressible and non-viscous
4. slightly affected by surface torque.

✅ Correct Answer: 3