# Hydraulics and Fluid Mechanics MCQ – Set 14

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## Q1. When a cylindrical vessel containing liquid is revolved about its vertical axis at a constant angular velocity, the pressure

(A) Varies as the square of the radial distance
(B) Increases linearly as its radial distance
(C) Increases as the square of the radial distance
(D) Decreases as the square of the radial distance

## Q2. The velocity corresponding to Reynold number of 2800, is called

(A) Sub-sonic velocity
(B) Super-sonic velocity
(C) Lower critical velocity
(D) Higher critical velocity

## Q3. The force present in a moving liquid is

(A) Inertia force
(B) Viscous force
(C) Gravity force
(D) All of these

## Q4. Whenever a plate is held immersed at some angle with the direction of flow of the liquid, it is subjected to some pressure. The component of this pressure, in the direction of flow of the liquid, is known as

(A) Lift
(B) Drag
(C) Stagnation pressure
(D) Bulk modulus

## Q5. In an external mouthpiece, the absolute pressure head at vena contracta is __ the atmospheric pressure head by an amount equal to 0.89 times the height of the liquid, above the vena contracta.

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

## Q6. Rain drops are spherical because of

(A) Viscosity
(B) Air resistance
(C) Surface tension forces
(D) Atmospheric pressure

(C) Laminar
(D) Vortex

## Q8. Manometer is used to measure

(A) Pressure in pipes, channels etc.
(B) Atmospheric pressure
(C) Very low pressure
(D) Difference of pressure between two points

Answer: (A) Pressure in pipes, channels etc.

## Q9. The discharge through an external mouthpiece is given by (where a = Cross-sectional area of the mouthpiece, and H = Height of liquid above the mouthpiece)

(A) 0.855 a.√(2gH)
(B) 1.855 aH.√(2g)
(C) 1.585 a.√(2gH)
(D) 5.85 aH.√(2g)

## Q10. According to Newton’s law of viscosity, the shear stress on a layer of a fluid is __ to the rate of shear strain.

(A) Equal to
(B) Directly proportional
(C) Inversely proportional
(D) None of these

## Q11. The celerity (velocity) of a pressure wave in a fluid is given by (where K = Bulk modulus, and ρ = Density of the fluid)

(A) K.ρ
(B) K/ρ
(C) ρ/K
(D) None of these

## Q12. When the pressure intensity at a point is more than the local atmospheric pressure, then the difference of these two pressures is called

(A) Gauge pressure
(B) Absolute pressure
(C) Positive gauge pressure
(D) Vacuum pressure

(A) N/m
(B) N/m2
(C) N/m3
(D) N-m

## Q14. Uniform flow 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 pleasure

Answer: (C) The magnitude and direction of the velocity do not change from point to point in the fluid

## Q15. Which of the following statement is wrong?

(A) A flow whose streamline is represented by a curve is called two dimensional flow.
(B) The total energy of a liquid particle is the sum of potential energy, kinetic energy and pressure energy.
(C) The length of divergent portion in a Venturimeter is equal to the convergent portion.
(D) A pitot tube is used to measure the velocity of flow at the required point in a pipe.

Answer: (C) The length of divergent portion in a Venturimeter is equal to the convergent portion.

## Q16. The resultant upward pressure of a fluid on a floating body is equal to the weight of the fluid displaced by the body. This definition is according to

(A) Buoyancy
(B) Equilibrium of a floating body
(C) Archimedes’ principle
(D) Bernoulli’s theorem

## Q17. The power transmitted through the pipe is maximum when the head lost due to friction is equal to

(A) One-fourth of the total supply head
(B) One-third of the total supply head
(C) One-half of the total supply head
(D) Two-third of the total supply head

## Q18. Property of a fluid by which its own molecules are attracted is called

(B) Cohesion
(C) Viscosity
(D) Compressibility

## Q19. For a floating body to be in equilibrium

(A) Meta centre should be above e.g.
(B) Centre of buoyancy and e.g. must lie on same vertical plane
(C) A righting couple should be formed
(D) All of the above

Answer: (D) All of the above

(A) 10 m/sec
(B) 25 m/sec
(C) 2 m/sec
(D) 50 m/sec