Hydraulic Machines-Fluid Machineries – Set 03

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Q1. The rise of liquid along the walls of a revolving cylinder about the initial level is _ the depression of the liquid at the axis of rotation.

(A) Same as
(B) Less than
(C) More than
(D) None of these

Answer: (A) Same as


Q2. A bucket of water is hanging from a spring balance. An iron piece is suspended into water without touching sides of bucket from another support. The spring balance reading will

(A) Increase
(B) Decrease
(C) Remain same
(D) Increase/decrease depending on depth of immersion

Answer: (C) Remain same


Q3. The most economical section of a trapezoidal channel is one which has hydraulic mean depth equal to

(A) 1/2 × depth
(B) 1/2 × breadth
(C) 1/2 × sloping side
(D) 1/4 × (depth + breadth)

Answer: (A) 1/2 × depth


Q4. A piece of wood having weight 5 kg floats in water with 60% of its volume under the liquid. The specific gravity of wood is

(A) 0.83
(B) 0.6
(C) 0.4
(D) 0.3

Answer: (B) 0.6


Q5. A flow is called sub-sonic, if the Mach number is

(A) Less than unity
(B) Unity
(C) Between 1 and 6
(D) More than 6

Answer: (A) Less than unity


Q6. Resultant pressure of the liquid in the case of an immersed body acts through

(A) Centre of gravity
(B) Centre of pressure
(C) Metacentre
(D) Centre of buoyancy

Answer: (B) Centre of pressure


Q7. Cavitation is caused by

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

Answer: (D) Low pressure


Q8. When a cylindrical vessel of radius (r) containing liquid is revolved about its vertical axis ω rad/s, then depth of parabola which the liquid assumes is

(A) ω.r/2g
(B) ω².r²/2g
(C) ω.r/4g
(D) ω².r²/4g

Answer: (B) ω².r²/2g


Q9. The rise or depression of liquid in a tube due to surface tension will increase in size of tube will

(A) Increase
(B) Remain unaffected
(C) May increase or decrease depending on the characteristics of liquid
(D) Decrease

Answer: (D) Decrease


Q10. The length of a liquid stream while flowing over a weir __ at the ends of the sill.

(A) Expands
(B) Does not change
(C) Contracts
(D) None of these

Answer: (C) Contracts


Q11. The volumetric change of the fluid caused by a resistance is known as

(A) Volumetric strain
(B) Volumetric index
(C) Compressibility
(D) Adhesion

Answer: (C) Compressibility


Q12. Euler’s dimensionless number relates the following

(A) Inertial force and gravity
(B) Viscous force and inertial force
(C) Viscous force and buoyancy force
(D) Pressure force and inertial force

Answer: (D) Pressure force and inertial force


Q13. For similarity, in addition to models being geometrically similar to prototype, the following in both cases should also be equal

(A) Ratio of inertial force to force due to viscosity
(B) Ratio of inertial force to force due to gravitation
(C) Ratio of inertial force to force due to surface tension
(D) All the four ratios of inertial force to force due to viscosity, gravitation, surface tension, and elasticity

Answer: (D) All the four ratios of inertial force to force due to viscosity, gravitation, surface tension, and elasticity


Q14. A flow is called hyper-sonic, if the Mach number is

(A) Less than unity
(B) Unity
(C) Between 1 and 6
(D) None of these

Answer: (D) None of these


Q15. The resultant upward pressure of the fluid on an immersed body is called

(A) Up-thrust
(B) Buoyancy
(C) Center of pressure
(D) All the above are correct

Answer: (B) Buoyancy


Q16. When a tube of smaller diameter is dipped in water, the water rises in the tube with an upward __ surface.

(A) Concave
(B) Convex
(C) Plane
(D) None of these

Answer: (A) Concave


Q17. Mercury is often used in barometer because

(A) It is the best liquid
(B) The height of barometer will be less
(C) Its vapour pressure is so low that it may be neglected
(D) Both (B) and (C)

Answer: (D) Both (B) and (C)


Q18. Hot wire anemometer is used to measure

(A) Pressure in gases
(B) Liquid discharge
(C) Pressure in liquids
(D) Gas velocities

Answer: (D) Gas velocities


Q19. A flow through a long pipe at constant rate is called

(A) Steady uniform flow
(B) Steady non-uniform flow
(C) Unsteady uniform flow
(D) Unsteady non-uniform flow

Answer: (A) Steady uniform flow


Q20. The speed of sound in a ideal gas varies directly as it’s

(A) Absolute temperature
(B) Temperature
(C) Density
(D) Modulus of elasticity

Answer: (A) Absolute temperature


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