# Hydraulic Machines-Fluid Machineries – Set 12

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## Q1. The flow in a pipe or channel is said to be non-uniform when

(A) The liquid particles at all sections have the same velocities
(B) The liquid particles at different sections have different velocities
(C) The quantity of liquid flowing per second is constant
(D) Each liquid particle has a definite path

Answer: (B) The liquid particles at different sections have different velocities

## Q2. Select the correct statement

(A) Local atmospheric pressure depends upon elevation of locality only
(B) Standard atmospheric pressure is the mean local atmospheric pressure a* sea level
(C) Local atmospheric pressure is always below standard atmospheric pressure
(D) A barometer reads the difference between local and standard atmospheric pressure

Answer: (B) Standard atmospheric pressure is the mean local atmospheric pressure a* sea level

## Q3. The depth of centre of pressure (h) for a vertically immersed surface from the liquid surface is given by (where IG = Moment of inertia of the immersed surface about horizontal axis through its centre of gravity, A = Area of immersed surface, and x = Depth of centre of gravity of the immersed surface from the liquid surface)

(A) (IG/Ax̅) – x̅
(B) (IG/x̅) – Ax̅
(C) (Ax̅/IG) + x̅
(D) (IG/Ax̅) + x̅

## Q4. A liquid compressed in cylinder has a volume of 0.04 m3 at 50 kg/cm² and a volume of 0.039 m3 at 150 kg/cm². The bulk modulus of elasticity of liquid is

(A) 400 kg/cm²
(B) 4000 kg/cm²
(C) 40 × 10⁵ kg/cm²
(D) 40 × 10⁶ kg/cm²

## Q5. Select the correct statement

(A) Weber’s number is the ratio of inertia force to elastic force
(B) Weber’s number is the ratio of gravity force to surface tension force
(C) Weber’s number is the ratio of viscous force to pressure force
(D) Weber’s number is the ratio of inertia force to surface tension force

Answer: (D) Weber’s number is the ratio of inertia force to surface tension force

## Q6. For a body floating in a liquid the normal pressure exerted by the liquid acts at

(A) Bottom surface of the body
(B) C.G. of the body
(C) Metacenter
(D) All points on the surface of the body

Answer: (D) All points on the surface of the body

## Q7. The flow in a pipe is neither laminar nor turbulent when Reynold number is

(A) Less than 2000
(B) Between 2000 and 2800
(C) More than 2800
(D) None of these

Answer: (B) Between 2000 and 2800

(A) Equal to
(B) One-half
(C) Three fourth
(D) Double

## Q9. Capillary action is due to the

(A) Surface tension
(B) Cohesion of the liquid
(C) Adhesion of the liquid molecules and the molecules on the surface of a solid
(D) All of the above

Answer: (D) All of the above

## Q10. Reynold’s number is the ratio of inertia force to

(A) Pressure force
(B) Elastic force
(C) Gravity force
(D) Viscous force

## Q11. Choose the wrong statement

(A) The center of buoyancy is located at the center of gravity of the displaced liquid
(B) For stability of a submerged body, the center of gravity of body must lie directly below the center of buoyancy
(C) If C.G. and center of buoyancy coincide, the submerged body must lie at neutral equilibrium for all positions
(D) All floating bodies are stable

Answer: (D) All floating bodies are stable

## Q12. The power transmitted through a pipe is (where w = Specific weight in N/m3, and Q = Discharge in m3/s)

(A) w × Q × H
(B) w × Q × hf
(C) w × Q (H – hf)
(D) w × Q (H + hf)

Answer:(C) w × Q (H – hf)

## Q13. Cavitation will begin when

(A) The pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid
(B) Pressure becomes more than critical pressure
(C) Flow is increased
(D) Pressure is increased

Answer: (A) The pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid

## Q14. The flow in which each liquid particle has a definite path and their paths do not cross each other is called

(A) One dimensional flow
(B) Streamline flow
(D) Turbulent flow

## Q15. The viscosity of water is __ than that of mercury.

(A) Higher
(B) Lower
(C) Same as
(D) None of these

## Q16. The bulk modulus of elasticity with increase in pressure

(A) Increases
(B) Decreases
(C) Remain constant
(D) Increases first up to certain limit and then decreases

## Q18. Hydrometer is used to determine

(A) Specific gravity of liquids
(B) Specific gravity of solids
(C) Specific gravity of gases
(D) Relative humidity

Answer: (A) Specific gravity of liquids

## Q19. The shear stress-strain graph for a Newtonian fluid is a

(A) Straight line
(B) Parabolic curve
(C) Hyperbolic curve
(D) Elliptical