Hydraulics and Fluid Mechanics MCQ – Set 16

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Q1. Euler’s equation in the differential form for the motion of liquids is given by

(A) dp/ρ + g.dz + v.dv = 0
(B) dp/ρ – g.dz + v.dv = 0
(C) ρ.dp + g.dz + v.dv = 0
(D) ρ.dp – g.dz + v.dv = 0

Answer: (A) dp/ρ + g.dz + v.dv = 0


Q2. A nozzle placed at the end of a water pipe line discharges water at a

(A) Low pressure
(B) High pressure
(C) Low velocity
(D) High velocity

Answer: (D) High velocity


Q3. The discharge over a rectangular notch is (where b = Width of notch, and H = Height of liquid, above the sill of the notch)

(A) (2/3) Cd × b × √(2gH)
(B) (2/3) Cd × b × √(2g) × H
(C) (2/3) Cd × b × √(2g) × H3/2
(D) (2/3) Cd × b × √(2g) × H2

Answer: (C) (2/3) Cd × b × √(2g) × H3/2


Q4. The loss of head at entrance in a pipe is (where v = Velocity of liquid in the pipe)

(A) v²/2g
(B) 0.5v²/2g
(C) 0.375v²/2g
(D) 0.75v²/2g

Answer: (B) 0.5v²/2g


Q5. In order to avoid tendency of separation at throat in a Venturimeter, the ratio of the diameter at throat to the diameter of pipe should be

(A) 1/16 to 1/8
(B) 1/8 to 1/4
(C) 1/4 to 1/3
(D) 1/3 to 1/2

Answer:(D) 1/3 to 1/2


Q6. The most efficient section of a channel is

(A) Triangular
(B) Rectangular
(C) Square
(D) Trapezoidal

Answer: (D) Trapezoidal


Q7. A notch is used to measure __ of liquids.

(A) Pressure
(B) Discharge
(C) Velocity
(D) Volume

Answer:(B) Discharge


Q8. At the center line of a pipe flowing under pressure where the velocity gradient is zero, the shear stress will be

(A) Minimum
(B) Maximum
(C) Zero
(D) Could be any value

Answer: (D) Could be any value


Q9. A weir is said to be broad crested weir, if the width of the crest of the weir is __ half the height of water above the weir crest.

(A) Equal to
(B) Less than
(C) More than
(D) None of these

Answer:(C) More than


Q10. Which of the following instrument can be used for measuring speed of an aeroplane?

(A) Venturimeter
(B) Orifice plate
(C) Pitot tube
(D) Rotameter

Answer: (C) Pitot tube


Q11. A hemispherical tank of radius (R) has an orifice of cross-sectional area (a) at its bottom and is full of liquid. The time required to empty the tank completely is

(A) 14π R1/2/15Cd × a √(2g)
(B) 14π R3/2/15Cd × a √(2g)
(C) 14π R5/2/15Cd × a √(2g)
(D) 14π R7/2/15Cd × a √(2g)

Answer: (C) 14π R5/2/15Cd × a √(2g)


Q12. Which of the following is the unit of kinematic viscosity?

(A) Pascal
(B) Poise
(C) Stoke
(D) Faraday

Answer: (C) Stoke


Q13. A uniform body 3 m long, 2 m wide and 1 m deep floats in water. If the depth of immersion is 0.6 m, then the weight of the body is

(A) 3.53 kN
(B) 33.3 kN
(C) 35.3 kN
(D) None of these

Answer: (C) 35.3 kN


Q14. The flow in which the velocity vector is identical in magnitude and direction at every point, for any given instant, is known as

(A) One dimensional flow
(B) Uniform flow
(C) Steady flow
(D) Turbulent flow

Answer: (B) Uniform flow


Q15. Mercury does not wet glass. This is due to property of liquid known as

(A) Adhesion
(B) Cohesion
(C) Surface tension
(D) Viscosity

Answer: (C) Surface tension


Q16. The siphon will work satisfactorily, if the minimum pressure in the pipe is __ vapour pressure of liquid.

(A) Equal to
(B) Less than
(C) More than
(D) None of these

Answer: (C) More than


Q17. The sheet of water flowing over a notch or a weir is known as

(A) Sill or crest
(B) Nappe or vein
(C) Orifice
(D) None of these

Answer: (B) Nappe or vein


Q18. An open tank containing liquid is made to move from rest with a uniform acceleration. The angle 0 which the free surface of liquid makes with the horizontal is such that (where a = Horizontal acceleration of the tank, and g = Acceleration due to gravity)

(A) tanθ = a/g
(B) tanθ = 2 a/g
(C) tanθ = a/2g
(D) tanθ = a2/2g

Answer: (A) tanθ = a/g


Q19. The pressure of fluid due to hammer blow is

(A) Directly proportional to density of fluid
(B) Inversely proportional to density of fluid
(C) Directly proportional to (density)1/2 of fluid
(D) Inversely proportional to (density)1/2 of fluid

Answer: (C) Directly proportional to (density)1/2 of fluid


Q20. A metal with specific gravity of ‘a’ floating in a fluid of same specific gravity ‘a’ will

(A) Sink to bottom
(B) Float over fluid
(C) Partly immersed
(D) Be fully immersed with top surface at fluid surface

Answer: (D) Be fully immersed with top surface at fluid surface


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