### Civil Engineering - Hydraulics MCQs Part 2

1. Liquids

A.
cannot be compressed
B.
do not occupy definite shape
C.
are not affected by change in pressure and temperature
D.
none of these.

2. The ratio of the percentagge error in the discharge and percentage error in the measurement of head over a triangular notch, is

A.
2/3
B.
3/2
C.
2/5
D.
5/2

3. The ratio of the inertia and gravitational force acting in any flow, ignoring other forces, is called

A.
Euler number
B.
Frode number
C.
Reynold number
D.
Weber number.

4. A rectangular channel 6 m wide and 3 m deep and having a bed slope as 1 in 2000 is running full. If Chezy's constant C = 54.8, pick up the correct specification of the channel from the following :

A.
hydraulic mean depth = 1.5 m
B.
Velocity of flow = 1.5 m/sec
C.
Rate of flow = 27 m3/sec
D.
All the above.

5. Non-over flow double curvature concrete arch, is provided in

A.
Bhakra dam
B.
Hirakund dam
C.
Nagarjuna Sagar dam
D.
Idukki dam.

6. For the most economical trapezoidal open channel,

A. half of the top width must be equal to one of the sloping sides
B. the hydraulic mean depth must be equal to half the depth of flow
C. the semicircle drawn with top width as diameter must touch the three sides of the channel
D. All of these.

7. Hydraulic ram is a device

A. for lifting water without an electric motor
B. for accelerating water flow
D. none of these.

8. Gauge pressure is

A. absolute pressure - atmospheric pressure
B. absolute pressure + atmospheric pressure
C. atmospheric pressure - absolute pressure
D. none of these.

9. The mouth piece shown in the below figure is generally known as

A. Internal mouth piece
B. Re-entrant mouth piece
C. Borda's mouth piece
D. All the above.

10. If S is the length of the crest, H is the height of water source of a weir whose length is L and discharge is Q m3/sec, the velocity of approach Vd is

A. 2gH
B.
C.
D.
E. none of these.

11. If jet of water coming out from a nozzle with a velocity 9.81 m/s, the angle of elevation being 30°, the time to reach the highest point is

A. 0.25 s
B. 0.50 s
C. 1.0 s
D. 1.5 s.

12. The discharge through a 100 mm diameter external mouth piece fitted to the side of a large vessel is 0.05948 m3/s. The head over the mouth piece is

A. 2 m
B. 2.5 m
C. 3.0 m
D. 4.0 m.

13. If cohesion between the molecules of a fluid is more than adhesion between the fluid and glass, the free level of fluid in a dipped glass tube will be

A. higher than the surface of liquid
B. same as the surface of liquid
C. lower than the surface of liquid
D. none of these.

14. The continuity equation

A. expresses the relationship between work and energy
B. relates the momentum per unit volume between two points on a stream line
C. relates mass rate of flow along a stream line
D. requires that Newton's second law of motion be satisfied at every point in fluid.

15. Water displaced by a floating wooden block of density 0.75, 5 m long, 2 m wide and 3 m high, is

A. 17.5 m3
B. 20.0 m3
C. 22.5 m3
D. 25 km3.

16. In pipe lines, a surge tank is provided

A. to relieve the pressure due to water hammer
C. to overflow the pipe line when suddenly closed
D. to remove the frictional loss in pipe.

17. Total head of a liquid particle in motion is the sum of

18. The velocity distribution of viscous fluid through a circular/pipe is :

A. hyperbolic
B. circular
C. parabolic
D. elliptical.

19. If u, v, w are the components of the velocity v of a moving particle, the equation represents

A. one diamensional flow
B. two dimensional flow
C. three dimensional flow
D. none of these.

20. Mercury is generally used in barometers because

A. its vaour pressure is practically zero
B. the height of the barometer will be less
C. it is a best liquid
D. both (a) and (b) above
E. both (b) and (c) above.

21. Flow in pipes is laminar if Reynold number is

A. less than 2100
B. more than 3000
C. between 2100 and 3000
D. none of these.

22. The terminal velocity (v) of a sphere of radius r and specific weight W, which travels vertically downwards in a liquid of viscosity μ and specific weight W, is

A.
B.
C.
D.

23. In flow, the liquid particles may possess

A. potential energy
B. kinetic energy
C. pressure energy
D. all the above.

24. Euler's equation for the motion of liquids assumes that

A. fluid is viscous
B. fluid is homogeneous and incompressible
C. velocity of flow is non-uniform over the section
D. flow is unsteady along the stream line.

25. The height of water level in a tank above the centre of a circular hole 2.5 cm in diameter is 50 m. The velocity of water flowing through the hole, is

A. 31.1 m/sec
B. 31.2 m/sec
C. 31.3 m/sec
D. 31.4 m/sec.

26. A steady uniform flow is through

A. a long pipe at decreasing rate
B. a long pipe at constant rate
C. an expanding tube at constant rate
D. an expanding tube at increasing rate
E. a long pipe at increasing rate.

27. Cavitation is caused by

A. Low pressure
B. High pressure
C. Low velocity
D. High velocity
E. None of these.

28. Mach number is the ratio of inertia force to

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

29. Hydraulic gradient is equal to difference in water surfaces

A.
B.
C.
D.

30. The main assumption of Bernoulli's equation is :

A. The velocity of energy of liquid particle, across any cross-section of a pipe is uniform
B. No external force except the gravity acts on the liquid
C. There is no loss of energy of the liquid while flowing
D. All the above.

31. The valve closure is said to be sudden if

A.
B.
C.
D.

32. If Re is the Renold's number, the coefficient of friction for laminar flow is

A.
B.
C.
D.

33. The length of pipe is L, velocity of flow of a liquid in the pipe is V. If t is the time in second required to close the valve, the head of pressure

A.
B.
C.
D. none of these.

34. For critical depth of flow of water in open channels, fc the specific energy must be :

A. minimum
B. maximum
C. average of maximum and minimum
D. None of these.

35. Kinematic viscosity of liquids by equation is determined by :

A. Redwood viscometer
B. Engler viscometer
C. Saybolt universal viscometer
D. None of these.

36. If the forces are due to inertia and gravity, and frictional resistance plays only a minor role, the design of the channels is made by comparing

A. Reynold number
B. Froude number
C. Weber number
D. Mach number.

37. The discharge over a Cipolletti weir of length 2.185 m when the head over the weir is 1 m, is

A. 2.0 m3
B. 2.5 m3
C. 3.0 m3
D. 4.0 m3.

38. The velocity of the fluid particle at the centre of the pipe section, is

A. minimum
B. maximum
C. equal throughout
D. none of these.

39. Due to decrease of diameter of the droplet, inside pressure intensity

A. increases
B. decreases
C. remains unaffected
D. None of these.

40. In order to avoid capillary correction, the minimum diameter of a manometer used for measuring pressure, should be

A. 2 mm
B. 4 mm
C. 6 mm
D. 8 mm
E. 10 mm.

41. When water flows over a rectangular suppressed weir, the negative pressure created beneath the nappe

A. increases the discharge
B. decreases the discharge
C. does not effect the discharge
D. none of these.

42. Barometres 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
E. very high pressure.

43. For most economical rectangular section of a channel, the depth is kept

A. one-fourth of the width
B. three times the hydraulic radius
C. half the width
D. hydraulic mean depth
E. none of these.

44. In a centrifugual pump casing, the flow of water leaving the impeller, is

A. rectilinear flow
C. free vortex motion
D. forced vertex.

45. In fluids, steady flow occurs when

A. conditions of flow change steadily with time
B. conditions of flow do not change with time at a point
C. conditions of flow remain the same at adjacent point
D. velocity vector remains constant at a point.

46. A cylinder 3 m in diameter and 4 m long retains water one side as shown in the below figure. If the weight of the cylinder is 2000 kgf, the vertical reaction at A is

A. 14,137 kgf
B. 5,863 kgf
C. 20,000 kgf
D. 18,000 kgf.

47. From a nozzle exposed to atmosphere, the liquid jet traverses

A. a straight line
B. a circular path
C. an elliptical path
D. a parabolic path.

48. To avoid the force of surface tension in an inclined manometer, the minimum angle of inclination is

A. 2°
B. 3°
C. 4°
D. 5°

49. An orifice is taken as large if

A. (H2 - H1) > H
B. (H2 - H1) > H/4
C. (H2 - H1) > H/2
D. (H2 - H1) > H/3

50. A closed cylindrical vessel of 100 cm diameter and 200 cm high is completely filled with a liquid (sp. weight 1600 kg/m3) when rotated about its vertical axis at 100 r.p.m. The total pressure on its lid, is

A. 459 kg
B. 549 kg
C. 945 kg
D. 954 kg
E. 95.4 kg.