Hydraulics and Fluid Mechanics MCQ – Set 25

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Q1. A glass tube of small diameter (d) is dipped in fluid. The height of rise or fall in the tube given by (where w = Specific weight of liquid, α = Angle of contact of the liquid surface, and σ = Surface tension)

(A) 4wd/σ cosα
(B) σ cosα/4wd
(C) 4σ cosα/wd
(D) wd/4σ cosα

Answer: (C) 4σ cosα/wd


Q2. Specific weight of water in S.I. units is equal to

(A) 1000 N/m3
(B) 10000 N/m3
(C) 9.81 × 103 N/m3
(D) 9.81 × 10⁶ N/m3

Answer: (C) 9.81 × 103 N/m3


Q3. When the flow parameters at any given instant remain same at every point, then flow is said to be

(A) Quasi-static
(B) Steady state
(C) Laminar
(D) Uniform

Answer: (D) Uniform


Q4. The resultant upward pressure of the fluid on an immersed body due to its tendency to uplift the submerged body is called

(A) Up-thrust
(B) Reaction
(C) Buoyancy
(D) Metacentre

Answer: (C) Buoyancy


Q5. The unit of kinematic viscosity in S. I. units is

(A) N-m/s
(B) N-s/m2
(C) m2/s
(D) N-m

Answer: (C) m2/s


Q6. The maximum efficiency of transmission through a pipe is

(A) 50 %
(B) 56.7 %
(C) 66.67 %
(D) 76.66 %

Answer: (C) 66.67 %


Q7. Water is a __ fluid.

(A) Real
(B) Ideal
(C) Newtonian
(D) Non-Newtonian

Answer: (C) Newtonian


Q8. Which of the following meters is not associated with viscosity?

(A) Red wood
(B) Say bolt
(C) Engler
(D) Orsat

Answer: (D) Orsat


Q9. Center of pressure on an inclined plane is

(A) At the Centroid
(B) Above the Centroid
(C) Below the Centroid
(D) At metacentre

Answer: (C) Below the Centroid


Q10. The viscosity of a liquid __ its rate of flow through a hole in a vessel.

(A) Effects
(B) Does not effect
(C) Both A and B
(D) None of these

Answer: (A) Effects


Q11. The hydraulic mean depth for a circular pipe of diameter (d) is

(A) d/6
(B) d/4
(C) d/2
(D) d

Answer: (B) d/4


Q12. The mass per unit volume of a liquid at a standard temperature and pressure is called

(A) Specific weight
(B) Mass density
(C) Specific gravity
(D) None of these

Answer: (B) Mass density


Q13. The shear stress between the two liquid layers is __ proportional to the distance between two layers.

(A) Directly
(B) Inversely
(C) Both A and B
(D) None of these

Answer: (B) Inversely


Q14. A liquid would wet the solid, if adhesion forces as compared to cohesion forces are

(A) Less
(B) More
(C) Equal
(D) Less at low temperature and more at high temperature

Answer: (B) More


Q15. Which of the following manometer has highest sensitivity?

(A) U-tube with water
(B) Inclined U-tube
(C) U-tube with mercury
(D) Micro-manometer with water

Answer: (D) Micro-manometer with water


Q16. Which of the following instrument can be used for measuring speed of a submarine moving in deep sea?

(A) Venturimeter
(B) Orifice plate
(C) Hot wire anemometer
(D) Pitot tube

Answer: (D) Pitot tube


Q17. Two dimensional flows occurs when

(A) The direction and magnitude of the velocity at all points are identical
(B) The velocity of successive fluid particles, at any point, is the same at successive periods of time
(C) The magnitude and direction of the velocity do not change from point to point in the fluid
(D) The fluid particles move in plane or parallel planes and the streamline patterns are identical in each plane

Answer: (D) The fluid particles move in plane or parallel planes and the streamline patterns are identical in each plane


Q18. The length AB of a pipe ABC in which the liquid is flowing has diameter (d1) and is suddenly enlarged to diameter (d2) at B which is constant for the length BC. The loss of head due to sudden enlargement is

(A) (v₁ – v₂)²/g
(B) (v₁² – v₂²)/g
(C) (v₁ – v₂)²/2g
(D) (v₁² – v₂²)/2g

Answer: (C) (v₁ – v₂)²/2g


Q19. The total pressure on an immersed surface inclined at an angle θ with the liquid surface is

(A) wA
(B) wx
(C) wAx
(D) wAx/sinθ

Answer: (C) wAx


Q20. The purpose of a surge tank is

(A) To control the pressure variations due to rapid changes in the pipe line flow
(B) To eliminate water hammer possibilities
(C) To regulate flow of water to turbines by providing necessary retarding head of water
(D) All of the above

Answer: (D) All of the above


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