### Civil Engineering - Hydraulics MCQs Part 3

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

A.

40 cm

40 cm

B.

41 cm

41 cm

C.

56 cm

56 cm

D.

60 cm

60 cm

E.

76 cm.

76 cm.

**Answer Option D**

2. A cylindrical vessel 40 cm high is revolved about its vertical axis so that the water touches the bottom when it just spills out. If the radius of the cylinder is 5 cm, the angular velocity of rotation, is

A.

2 rad/sec

2 rad/sec

B.

3 rad/sec

3 rad/sec

C.

4 rad/sec

4 rad/sec

D.

5 rad/sec

5 rad/sec

E.

none of these.

none of these.

**Answer Option A**

3. 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

A.

Froude number

Froude number

B.

Weber number

Weber number

C.

Reynold number

Reynold number

D.

Mach number.

Mach number.

**Answer Option B**

4. In Newton's viscosity equation , the coefficient (μ) is known as coefficient of

A.

viscosity

viscosity

B.

absolute viscosity

absolute viscosity

C.

dynamic viscosity

dynamic viscosity

D.

simple viscosity

simple viscosity

E.

all the above.

all the above.

**Answer Option E**

5. An error of 1% in measuring the head of water over the crest of a triangular notch, produces an error in the discharge which is equal to

A.

1.25%

1.25%

B.

1.5%

1.5%

C.

2.0%.

2.0%.

D.

2.5%

2.5%

**Answer Option D**

6. Which one of the following equation is applicable to unsteady flow in open channels :

A.

B.

C.

D.

**Answer Option D**

7. Dimensions of the dynamic viscosity (μ) are

A. MLT-2

B. M-1L-1T-1

C. ML-1T-2

D. ML-1T-1.

**Answer Option D**

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

A. 2.4 m

B. 6.4 m

C. 10.0 m

D. 5.0 m.

**Answer Option B**

9. 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

A. 15 m

B. 20 m

C. 30 m

D. 40 m

E. 60 m.

**Answer Option D**

10. If Cv, Cc, Cd and Cr are the hydraulic coefficients of an orifice, then

A. Cd = Cc . Cv

B. Cr = 1 + Cv2/Cd

C. Cv = Cc + Cd

D. Cc = Cv/Cd

**Answer Option A**

11. Atmospheric pressure varies with

A. altitude

B. temperature

C. weather conditions

D. all of the above.

**Answer Option D**

12. The magnitude of water hammer in a pipe depends upon

A. speed at which value is closed

B. length of the pipe line

C. elastic properties of the pipe material

D. elastic properties of the following liquid

E. all the above.

**Answer Option E**

13. 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

A. laminar

B. turbulent flow

C. uniform flow

D. non-uniform flow.

**Answer Option B**

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

A. greater than the depression of the liquid at the axis of rotation

B. lesser than the depression of the liquid at the axis of rotation

C. the same as the depression of the liquid at the axis of rotation

D. none of these.

**Answer Option C**

15. Fluids change the volume under external presssure due to

A. plasticity

B. viscosity

C. compressibility

D. none of these.

**Answer Option C**

16. Discharge over an ogee weir remains the same as that of

A. sharp crested weir

B. triangular weir

C. cippoletti weir

D. drowned weir.

**Answer Option C**

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

A. free nappe

B. depressed nappe

C. clinging nappe

D. none of these.

**Answer Option C**

18. The best side slope for most economical trapezoidal section, is

A. 30°

B. 45°

C. 60°

D. None of these.

**Answer Option C**

19. The following is not a laminar flow

A. Flow of oil in measuring instruments

B. Flow in beds in ground water

C. Rise of water in plants through roots

D. Flow of blood in the arteries of human body

E. Flow in water pipe lines.

**Answer Option E**

20. Which one of the following statements is true ?

A. The value of kinetic energy correction factor for turbulent flow lies between 1.03 to 1.06

B. The value of kinetic energy correction factor for laminar flow is 2

C. The practical value of kinetic energy correction factor for turbulent flow is unity

D. all the above.

**Answer Option D**

21. Uniform flow is said to occur when

A. size and shape of the cross-section in a particular length remain constant

B. size and shape of the cross-section change along a length

C. frictional loss in the particular length of the channel will the more than the drop in its elevation

D. frictional loss in the particular length of the channel, will be less than the drop in elevation.

**Answer Option A**

22. For the most economical trapezoidal section of a channel with regards to discharge, the required condition, is

A. half of top width = sloping side

B. hydraulic depth = half the depth

C.

D. perpendiculars drawn from the centre of the top width on to the bottom sloping side, are all equal

E. all the above.

**Answer Option E**

23. Molecules of fluids get attracted due to

A. capillarity action

B. surface tension

C. adhesion

D. cohesion

E. none of these.

**Answer Option C**

24. Cappoletti weir is a

A. rectangular weir whose length is kept 3 times the height of the water above sill

B. triangular weir whose notch angle is 90°

C. trapezoidal weir, whose sides slope 1 horizontal to 2 verticals

D. a combination of rectangular and triangular weirs.

**Answer Option C**

25. On an inclined plane, centre of pressure is located

A. at the centroid

B. above the centroid

C. below the centroid

D. anywhere.

**Answer Option C**

26. For pipes not running full, the hydraulic mean depth is given by

A. m = r(θ - sin θ)

B.

C.

D.

**Answer Option B**

27. Atmospheric pressure is equal to water column head of

A. 9.81 m

B. 5.0 m

C. 10.30 m

D. 7.5 m.

**Answer Option C**

28. Shear stress is directly proportional to

A. the velocity

B. the shear strain

C. the viscosity

D. the velocity.

**Answer Option B**

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

A. at the inlet

B. at the outlet

C. at the summit

D. at any point between intet and outlet.

**Answer Option C**

30. Pick up the correct statement from the following :

A. Total energy gradient is the graphical representation of the total head at any section of a pipe line

B. Vertical distance between the total energy line and hydraulic grade line is equal to the velocity head

C. Vertical distance between the total energy line and total energy gradient represents loss of head

D. all the above.

**Answer Option D**

31. A fluid particle may possess the displacement of

A. translation

B. rotation

C. distortion

D. all the above.

**Answer Option D**

32. In Chezy's formula V = C mi

A. V is the mean velocity of flow

B. m is the hydraulic mean depth

C. i is the loss of head per unit length of pipe

D. All the above.

**Answer Option D**

33. Pick up the correct statement from the following :

A. 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

B. 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.

C. both (a) and (b)

D. Neither (a) nor (b).

**Answer Option C**

34. If total head available at the inlet of pipe and f1 is the loss of head due to friction in the pipe, the maximum efficiency of transmission of power (ηmax) is

A. 1/2

B. 2/3

C. 3/4

D. 4/5

**Answer Option B**

35. Piezometers are used to measure

A. pressure in water channels, pipes etc.

B. difference in pressure at two points

C. atmospheric pressure

D. very low pressure.

**Answer Option D**

36. Most economical section of a triangular channel, is

A. equilateral triangle

B. right angled triangle

C. isosceles triangle with 45° vertex angle

D. right angled triangle with equal sides.

**Answer Option D**

37. In an open tube, free surface of mercury remains

A. horizontal

B. curved upwards

C. curved downwards

D. none of these.

**Answer Option C**

38. The equation for the viscosity, is suggested

A. Bernoulli

B. Newton

C. Chezy

D. Bezin

E. Helmholtz.

**Answer Option B**

39. The value of momentum correction factor (β) for a laminar flow through a circular pipe, is

A. 1/2

B. 2/3

C. 3/4

D. 4/3

E. 3/2

**Answer Option D**

40. Manometers are used to measure

A. pressure in water channels, pipes etc.

B. difference in pressure at two points

C. atmospheric pressure

D. very low pressure.

**Answer Option A**

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

A. head loss in the pipe due to friction

B. twice the head loss in the pipe due to friction

C. thrice the head loss in the pipe due to friction

D. four times the head loss in the pipe due to friction.

**Answer Option C**

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

A. 1

B. 2

C. 3

D. 4

**Answer Option D**

43. Flow in pipes is turbulent if Reynold number is

A. less than 2100

B. more than 3000

C. between 2100 and 3000

D. none of these.

**Answer Option B**

44. Back water curve is caused if

A. friction head loss is more than the bed slope

B. pressure is due to weir in the channel

C. there is an increase in width of the channel

D. none of these.

**Answer Option B**

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

A. one-half of the total head supplied

B. one-third of the total head supplied

C. one-fouth of the total head supplied

D. equal to the total head supplied.

**Answer Option B**

46. The specific weight of water is 1000 kg/m3

A. at normal pressure of 760 mm

B. at 4°C temperature

C. at mean sea level

D. all the above.

**Answer Option D**

47. Specific weight of liquid

A. remains constant at every place

B. does not remain constant at every place

C. varies from place to place on the earth

D. does not vary on any other planet.

**Answer Option D**

48. Manning's formula is used for

A. flow in open channels

B. head loss due to friction in open channels

C. head loss due to friction in pipes flowing full

D. flow in pipes.

**Answer Option B**

49. A non-uniform steady flow is through

A. a long tube at a decreasing rate

B. an expanding tube at constant rate

C. an expanding tube at increasing rate

D. a long pipe at increasing rate.

**Answer Option B**

50. An ideal fluid is

A. incompressible

B. compressible

C. compressible and non-viscous

D. slightly affected by surface torque.

**Answer Option C**

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