### Civil Engineering - Hydraulics MCQs Part 4

1. Equation of continuity of flow is based on the principle of conservation of

A.
mass
B.
momentum
C.
force
D.
none of these.

2. Pick up the correct statement from the following :

A.
Discharge over a triangular notch is proportional to H5/2
B.
Discharge over a rectangular notch is proportional to H3/2
C.
Both (a) and (b)
D.
Neither (a) nor (b).

3. The flow in open channel is said to be subcritical if the Froude number is

A.
less than 1.0
B.
equal to 1.0
C.
greater than 1.0
D.
none.

4. In C.G.S. system the unit of visocity is

A.
dyne
B.
joule
C.
poise
D.
Newton
E.
none of these.

5. The ratio of the percentage error in the discharge and percentage error in the measurement of head, over rectangular notch, is

A.
1/2
B.
2/3
C.
3/2
D.
3/4

6. In steady flow, which one of the following changes with time

A. velocity
B. pressure
C. density
D. none of these.

7. The notch angle for maximum discharge over a triangular notch, is

A. 30°
B. 60°
C. 90°
D. 120°

8. In an inclined pipe, the pressure difference at its two ends is due to

A. sudden head drop at inlet
E. all the above.

9. Weber number is the ratio of inertia force to

A. surface tension
B. gravitational force
C. elasticity
D. viscosity.

10. Though angle of deviation of liquid is more in internal mouth piece, the contraction of the jet, is

A. more in the internal mouth piece
B. less in the internal mouth piece
C. equal to external mouth piece
D. none of these.

11. The width of a weir with end contraction, is

A. equal to the width of the channel
B. less than the width of the channel
C. half the width of the channel
D. none of these.

12. The ratio of time for completely emptying the hemispherical tank and circular horizontal tank of equal radii both fitted with similar orifices at their bottoms is :

A.
B.
C.
D.

13. An open container filled with water is moved vertically upward with a uniform linear acceleration. The pressure at its bottom will be

A. greater than static pressure
B. equal to static pressure
C. lesser than static pressure
D. none of these.

14. The gases are considered incompressible if Match number is

A. equal to 1.0
B. equal to 1.5
C. is more than 0.5
D. less than 0.2

15. The flow in which each liquid particle has a definite path and the paths of adjacent particles do not cross each other, is called

A. stream line flow
B. uniform flow
D. turbulent flow.

16. To replace a pipe of diameter D by n parallel pipes of diameter d, the formula is

A.
B.
C.
D.
E.

17. The dimensionless parameter not applicable to flowing liquids, is

A. Reynold number
B. Weber number
C. Pressure coefficient
D. Kinematic viscosity
E. Friction factor.

18. The pressure rise due to water hammer depends upon

A. the velocity of flow of water in the pipe
B. the length of pipe
C. time taken to close the valve
D. the elasticity of the pipe material
E. All of above.

19. In a two dimensional flow if the components of the velocity are u = ax ; v = by, the point where no motion occurs, is known as

A. critical point
B. neutral point
C. stagnation point
D. stationary point
E. none of these.

20. Most economical section of a circular channel for maximum velocity, is if,

A. depth of water = 0.810 diameter
B. hydraulic mean depth = 0.304 diameter
C. wetted perimeter = 2.245 diameters
D. all the above.

21. For a most economical rectangular channel, the width of the channel must be

A. equal to depth of flow
B. twice the depth of flow
C. half the depth of flow
D. None of these.

22. If a1 and a2 are the cross-sectional areas of a tank and orifice, h the height of water level in tank above the centre of the orifice, the velocity of approach is given by

A.
B.
C.
D.

23. The hydrostatic force acts through

A. centre of pressure
B. centre of top edge
C. centre of bottom edge
D. metacentre.

24. In an inclined position, a venturimeter records

D. none of these.

25. If E1 and E2 are the specific energies at the start of back water curve and at the maximum rise of water respectively and ib and ie are the head slope and the energy line slope respectively, the length of back water (L) is given by

A.
B.
C.
D. None of these.

26. The velocity of flow at the critical depth (hc) is called critical velocity (Vc) which is equal to

A. Vc = g x hc
B. g x hc
C.
D. None of these.

27. In a short cylindercial external mouthpiece, the venacontracta occurs at a distance from the outlet of orifice equal to

A. diameter of the orifice
B. one-fourth the diameter of the orifice
C. one-third the diameter of the orifice
D. two-third the diameter of the orifice

28. If the pressure at the inlet of a pipe is 90 kg/cm2 and pressure drop over the pipe line is 10 kg/cm2, the efficiency of transmission, is

A. 66.6%
B. 77.7%
C. 55.5%
D. 88.8%.

29. Pick up the incorrect statement from to following regarding triangular notch :

A. For measuring low discharge, it gives more accurate result
B. Only one reading (i.e. H) is required for computation of discharge
C. Ventilation is necessary
D. None of these.

30. The flow in a channel is said to be non-uniform, if

A. free water surface of an open channel is not parallel to the bed of channel
B. head needed to overcome frictional reistance is less than the drop in elevation of channel bed
C. head needed to overcome frictional resistance is more than the drop in elevation of channel bed
D. all the above.

31. If H is the depth of water retained by a vertical wall, the height of centre of pressure above the bottom is

A.
B.
C.
D.

32. For maximum power transmission through a nozzle, (where hf is the head lost due to friction)

A.
B.
C.
D.

33. Mass density of liquid (ρ) is given by

A.
B.
C.
D. all the above.

34. 'Flow net' can be drawn only if the flow is

A. turbulent
B. rotational
C. distortion
D. none of these.

35. The flow in open channel is laminar if the Reynold number is

A. less than 500
B. more than 500
C. 1000
D. none of these.

36. Centre of buoyancy is

A. centroid of the floating body
B. centroid of the fluid displaced
C. centre of pressure of the displaced liquid
D. none of these.

37. The intensity of pressure due to sudden closure of a valve of a pipe in which water flows with velocity v, is directly proportional to :

A. square root of the bulk modulus of elasticity of water
B. bulk modulus of elasticity of water
C. specific weight of water
D. none of these.

38. The initial difference between liquid levels of two identical cylindrical vessels having their area of cross-section A, is H. Flow time T from one vessel to another through an orifice having coefficient of discharge Cd and area a will be

A.
B.
C.
D.

39. Total energy line is

D. All the above.

40. For critical flow, the Froude number is :

A. 1.0
B. less than 1.0
C. more than 1.0
D. 2

41. A stepped notch is a combination of

A. rectangular notches of different sizes
B. triangular notches of different sizes
C. rectangular and triangular notches
D. all the above.

42. The centre of pressure of a vertical plane immersed in a liquid is at

A. centre of higher edge
B. centre of lower edge
C. centroid of the area
D. none of these.

43. The ratio of the hydraulic radius of a pipe running full to the hydraulic radius of a square section of a channel whose side is equal to the diameter of the pipe, is

A. 1
B.
C.
D.

44. A body of dimensions 1.5 m x 1.0 m x 2 m weighs 3000 kg in water. Its specific gravity is

A. 0.8
B. 0.9
C. 1.0
D. 1.1

45. An orifice is called a large orifice if water head, is

A. twice the diameter of the orifice
B. thrice the diameter of the orifice
C. four times the diameter of the orifice
D. five times the diameter of the orifice.

46. When a liquid rotates at constant angular velocity about a vertical axis of a rigid body, the pressure

A. increases linearly to its radial distance
B. varies inversely as the altitude along any vertical line
C. varies as the square of the radial distance
D. decreases as the square of the radial distance
E. none of these.

47. For the two dimensional flow, the stream function is given by ψ = 2xy. The velocity at a point (3, 4) is

A. 6 m/sec
B. 8 m/sec
C. 10 m/sec
D. 12 m/sec
E. 15 m/sec.

48. A floating body attains stable equilibrium if its metacentre is

A. at the centroid
B. above the centroid
C. below the centroid
D. anywhere.

49. The unit of the viscosity is

A. kg sec/m2
B. Newton sec per m2
C. Newton-sec2/m3
D. m2 per sec.