Hydraulic Machines-Fluid Machineries – Set 06

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Q1. Choose the wrong statement

(A) The horizontal component of the hydrostatic force on any surface is equal to the normal force on the vertical projection of the surface
(B) The horizontal component acts through the center of pressure for the vertical projection
(C) The vertical component of the hydrostatic force on any surface is equal to the weight of the volume of the liquid above the area
(D) The vertical component passes through the center of pressure of the volume

Answer: (D) The vertical component passes through the center of pressure of the volume


Q2. An orifice is said to be large, if

(A) The size of orifice is large
(B) The velocity of flow is large
(C) The available head of liquid is more than 5 times the height of orifice
(D) The available head of liquid is less than 5 times the height of orifice

Answer: (D) The available head of liquid is less than 5 times the height of orifice


Q3. When the Mach number is between __ the flow is called super-sonic flow.

(A) 1 and 2.5
(B) 2.5 and 4
(C) 4 and 6
(D) 1 and 6

Answer: (D) 1 and 6


Q4. The ratio of the inertia force to the __ is called Euler’s number.

(A) Pressure force
(B) Elastic force
(C) Surface tension force
(D) Viscous force

Answer: (A) Pressure force


Q5. Fluid is a substance that

(A) Cannot be subjected to shear forces
(B) Always expands until it fills any container
(C) Has the same shear stress at a point regardless of its motion
(D) Cannot remain at rest under action of any shear force

Answer: (D) Cannot remain at rest under action of any shear force


Q6. The increase in pressure at the outer edge of a drum of radius (r) completely filled up with liquid of density (ρ) and rotating at (ω) rad/s is

(A) ρ ω2 r2
(B) 2ρ ω2 r2
(C) ρ ω2 r2/2
(D) ρ ω2 r2/4

Answer: (C) ρ ω2 r2/2


Q7. Reynolds number is significant in

(A) Supersonics, as with projectile and jet propulsion
(B) Full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
(C) Simultaneous motion through two fluids where there is a surface of discontinuity, gravity forces, and wave making effect, as with ship’s hulls
(D) All of the above

Answer: (B) Full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.


Q8. The center of gravity of the volume of the liquid displaced by an immersed body is called

(A) Center of gravity
(B) Center of pressure
(C) Metacenter
(D) Center of buoyancy

Answer: (D) Center of buoyancy


Q9. The kinematic viscosity of an oil (in stokes) whose specific gravity is 0.95 and viscosity 0.011 poise, is

(A) 0.0116 stoke
(B) 0.116 stoke
(C) 0.0611 stoke
(D) 0.611 stoke

Answer: (A) 0.0116 stoke


Q10. A perfect gas

(A) Has constant viscosity
(B) Has zero viscosity
(C) Is in compressible
(D) None of the above

Answer:(D) None of the above


Q11. A Piezometer tube is used only for measuring

(A) Low pressure
(B) High pressure
(C) Moderate pressure
(D) Vacuum pressure

Answer: (C) Moderate pressure


Q12. Two pipe systems can be said to be equivalent, when the following quantities are same

(A) Friction loss and flow
(B) Length and diameter
(C) Flow and length
(D) Friction factor and diameter

Answer: (A) Friction loss and flow


Q13. The variation in the volume of a liquid with the variation of pressure is called its

(A) Surface tension
(B) Compressibility
(C) Capillarity
(D) Viscosity

Answer: (B) Compressibility


Q14. In one dimensional flow, the flow

(A) Is steady and uniform
(B) Takes place in straight line
(C) Takes place in curve
(D) Takes place in one direction

Answer: (B) Takes place in straight line


Q15. Surface tension

(A) Acts in the plane of the interface normal to any line in the surface
(B) Is also known as capillarity
(C) Is a function of the curvature of the interface
(D) Decreases with fall in temperature

Answer: (A) Acts in the plane of the interface normal to any line in the surface


Q16. The height of a water column equivalent to a pressure of 0.15 MPa is

(A) 15.3 m
(B) 25.3 m
(C) 35.3 m
(D) 45.3 m

Answer: (A) 15.3 m


Q17. The line of action of the buoyant force acts through the Centroid of the

(A) Submerged body
(B) Volume of the floating body
(C) Volume of the fluid vertically above the body
(D) Displaced volume of the fluid

Answer: (D) Displaced volume of the fluid


Q18. In open channels, the specific energy is the

(A) Total energy per unit discharge
(B) Total energy measured with respect to the datum passing through the bottom of the channel
(C) Total energy measured above the horizontal datum
(D) Kinetic energy plotted above the free surface of water

Answer: (B) Total energy measured with respect to the datum passing through the bottom of the channel


Q19. A piece of metal of specific gravity 13.6 is placed in mercury of specific gravity 13.6, what fraction of it volume is under mercury?

(A) The metal piece will simply float over the mercury
(B) The metal piece will be immersed in mercury by half
(C) Whole of the metal piece will be immersed with its top surface just at mercury level
(D) Metal piece will sink to the bottom

Answer: (C) Whole of the metal piece will be immersed with its top surface just at mercury level


Q20. In an immersed body, centre of pressure is

(A) At the centre of gravity
(B) Above the centre of gravity
(C) Below be centre of gravity
(D) Could be above or below e.g. depending on density of body and liquid

Answer: (C) Below be centre of gravity


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