### Civil Engineering - Hydraulics MCQs Part 5

1. Water flows through a convergent mouthpiece of diameter 4 cm at convergence under a head of 3 metres. If the maximum vacuum pressure is 9 metres of water, the maximum diameter of divergence, to aviod separation of flow, is

A.
4 cm
B.
6 cm
C.
2 cm
D.
23 cm.

Answer Option C

2. An ideal fluid

A.
is frictionless and incompressible
B.
obeys Newton's law of velocity
C.
is similar to gas
D.
is very viscous.

Answer Option A

3. In C.G.S. system the units of kinematic viscosity, is

A.
stoke
B.
poise
C.
Newton
D.
none of these.

Answer Option A

4. A triangular notch is preferred to a rectangular notch because

A.
only one reading is required
B.
its formula is simple to remember
C.
it gives more accurate results for low discharge
D.
it measures a wide range of flows accurately
E.
all the above.

Answer Option E

5. In case of laminar flow through a circular pipe,

A.
momentum correction factor is 1.33
B.
energy correction factor is 2.00
C.
both (a) and (b)
D.
Neither (a) nor (b).

Answer Option C

6. The pressure less than atmospheric , pressure, is known

A. suction pressure
B. vacuum pressure
C. negative gauge pressure
D. all the above.

Answer Option D

7. If H is the difference of liquid levels on two sides of an orifice (width b, depth d), the discharge through the orifice will be

A. Cdbd22gH
B. Cdb2d2gH
C. Cdbd2gh
D. Cdbd.2g H1/2.

Answer Option C

8. A load w is rolled a distance d across the deck of a ship of weight W, due to which the ship heels through θ°. The metacentric height of the ship, is

A.
B.
C.
D.

Answer Option C

9. A rise or fall of liquid in a glass tube of a very small diameter when dipped is

A. directly proportional to the force per unit length of periphery
B. direcly proportional to the sine of the angle of contact
C. directly proportional to the specific weight of liquid
D. inversely proportional to the diameter of the glass tube.

Answer Option C

10. To measure very low pressure, we use

A. barometers
B. piezometers
C. manometers
D. differential manometers.

Answer Option C

11. If a pitot tube is placed with its nose facing down stream, the liquid

A. does not rise in the tube
B. rises in the tube to a height
C. falls in the tube to a depth
D. none of these.

Answer Option C

12. The discharge through an internal mouth piece is more if its length is

A. < diameter
B. < diameter
C. ≥ diameter
D. none of these.

Answer Option C

13. A spherical load 900 kg is rolled through 9.8 m across the deck of a ship weighing 10, 000 kg. If the metacentric height of the ship is 5 metres, the angle of heel, is

A. 10° 5'
B. 10° 10'
C. 10° 15'
D. 10° 20'

Answer Option C

14. Pick up the correct statement from the following :

A. In incompressible flow the density of a fluid remains constant
B. In compressible flow, the density of a fluid changes from point to point
C. In uniform flow, the velocity of a fluid does not change with respect to length of flow direction
D. All the above.

Answer Option D

15. Pick up the incorrect statement from the following :

A. In radial flow, fluid flows such that pressure and velocity at any point change with respect to its distance from the central axis
B. In radial flow, velocity of flow is in a radial direction
C. In radial flow, flow may take place radially inward to or outward from the centre
D. In radial flow, flow is one dimensional with stream lines parallel.

Answer Option D

16. Chezy's formula is used to determine

A. head loss due to friction in pipe
B. velocity of flow in pipe
C. velocity of flow in open channels
D. none of these.

Answer Option C

17. The metacentric height of a body equals the distance between

A. the centre of gravity and centre of buoyancy
B. the metacentre and centre of gravity
C. the centre of buoyancy and metacentre
D. none of these.

Answer Option B

18. Discharge through a totally submerged orifice, is directly proportional to

A. difference in elevation of water surfaces
B. square root of the difference in elevation of water surface
C. square root of the opening
D. reciprocal of the area of the opening
E. none of these.

Answer Option B

19. Frictional loss of head includes the loss of energy due to

A. viscosity
B. turbulence
C. both (a) and (b)
D. none of these.

Answer Option D

20. The length of hydraulic jump is roughly

A. 2 to 3 times its height
B. 3 to 5 times its height
C. 5 to 7 times its height
D. None of these.

Answer Option C

21. To ensure that water does not rise more than 100 cm above the crest, for a discharge of 5.00 m3/sec, the length of water will be

A. 2.48 m
B. 2.49 m
C. 2.50 m
D. 2.51 m.

Answer Option B

22. For a most economical trapezoidal open channel, the half of the top width must be equal to

A. the bed width
B. one sloping side
C. the depth of flow
D. None of these.

Answer Option B

23. Pick up the correct statement regarding convergent divergent mouth piece from the following :

A. It converges upto Venacontracta and then diverges
B. In this mouth piece there is no loss of energy due to sudden enlargement
C. The coefficient of discharge is unity
D. All the above.

Answer Option D

24. The value of kinetic energy correction factor (a) for a laminar flow through a circular pipe, is

A. 0.5
B. 1.0
C. l.5
D. 2.0
E. 2.5

Answer Option D

25. The formula Q = m x L x 2g x H3/2 where was suggested by :

A. Bazin
B. Francis
C. Cipolletti
D. None of these.

Answer Option A

26. One metric slug is equal to

A. 1 kg wt
B. 9.81 kg wt
C. 9.81 kg mass
D. 0.98 kg wt.

Answer Option C

27. Falling drops of water become spheres due to

A. adhesion
B. cohesion
C. surface tension
D. viscosity.

Answer Option C

28. The most efficient channel section, is

A. semi-circular
B. rectangular
C. triangular
D. half hexagon in the form of trapezoid.

Answer Option D

29. With a clinging nappe of a weir, the excess discharge, is

A. 6% to 7%
B. 8% to 10%
C. 18% to 20%
D. 25% to 30%
E. 30% to 40%.

Answer Option D

30. For steady flow in open channels, which one of the following does not change :

A. depth of flow
B. velocity of flow
C. rate of flow
D. All of these.

Answer Option D

31. If v1 and v2 are the velocities of flow before and after sudden enlargement in a pipe, the head loss given by Carnot and Borda equation, is

A. (v22 - v12)/2g
B. (v1 - v2)2/2g
C. (v2 - v1)2/2g
D. (v1 + v2)2/2g.

Answer Option B

32. Equation of continuity of fluids is applicable only if

A. flow is steady
B. flow is compressive
C. flow is one dimensional
D. velocity is uniform over the cross-sections
E. all the above.

Answer Option E

33. The flow in open channel is said to be critical if the Froude number is :

A. less than 1.0
B. equal to 1.0
C. greater than 1.0
D. None of these.

Answer Option B

34. An orifice is an opening in a vessel with

A. closed perimeter of regular shape through which water flows
B. the water level of the liquid on the up stream side is below the top of the orifice
C. partially full flow
D. prolonged sides having length of 2 to 3 diameters of the opening in thick wall.

Answer Option A

35. The imaginary line drawn such that the tangents at its all points indicate the direction of the velocity of the fluid particles at each point, is called

A. path line
B. stream line
C. potential line
D. streak line.

Answer Option B

36. A nozzle is fitted at the end of a pipe whose length is 320 m and diameter is 10 cm. If the value of f = 0.01, the diameter of the nozzle for the maximum transmission of power through the nozzle is

A. 2.4 cm
B. 2.5 cm
C. 2.6 cm
D. 2.7 cm.

Answer Option B

37. When the whole fluid mass rotates either due to fluid pressure or gravity or rotation previously imparted, the motion is known as

A. free vortex
B. forced vortex
C. non-potential vortex
D. rotational vortex.

Answer Option A

38. The ratio of the maximum height to which a jet inclined through θ rises to its total horizontal span is

A. sin θ
B. cos θ
C. tan θ
D. cot θ.

Answer Option C

39. For solving the problems is hydraulic engineering, the velocity used is

A. velocity at the centre of pipe section
B. average velocity of flow over a section
C. mean of the velocities at the centre and that along the pipe surface
D. none of these.

Answer Option B

40. The shape of fire hose nozzle is generally kept

A. divergent
B. convergent
C. convergent divergent
D. cylindrical.

Answer Option B

41. The dimensions MLT-2 refers to

A. specific weight
B. force
C. discharge
D. none of these.

Answer Option B

42. The line joining the points to which the liquid rises in vertical piezometer tubes fitted at different cross-sections of a conduit, is known as

A. hydraulic gradient
B. piezometric line
C. pressure grade line
D. hydraulic grade line
E. all the above.

Answer Option E

43. Practical fluids possess

A. viscosity
B. surface tension
C. compressibility
D. all the above.

Answer Option D

44. The depth of the centre of pressure on a vertical rectangular gate (4 m wide, 3 m high) with water upto top surface, is

A. 1.0 m
B. 1.5 m
C. 2.0 m
D. 2.5 m.

Answer Option C

45. The differential equation dp/ρ + gdz + vdv = 0 for a fluid motion is suggested by

A. Bernoulli
B. Cauchy-Riemann
C. Laplace
D. Leonard Euler.

Answer Option D

46. An open container filled with water is moved vertically downward 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.

Answer Option C

47. For uniform flow in canals

A. there is a balance between the frictional loss and drop in elevation of the channel
B. bed and free water surfaces of a channel are parallel to each other
C. bed of channel represents the hydraulic gradient
D. all the above.

Answer Option D

48. If H is height of the liquid above the sill, the effect of end contractions, according to Francis formula, is

A. 0.1 H
B. 0.2 H
C. 0.3 H
D. 0.4 H
E. 0.5 H.

Answer Option A

49. Pick up the correct statement from the following :

A. For maximum velocity of flow, the depth of water in the circular channel must be 0.81 times the diameter of the channel
B. For maximum velocity, the hydraulic mean depth must be 0.3 times the diameter of circular channel
C. For maximum discharge the depth of flow must be 0.95 times the diameter of circular channel
D. All the above.

Answer Option D

50. The velocity of flow (v) at the outlet of a syphon of length l, is given by

A.
B.
C.
D.

Answer Option B