fluid mechanics mechanical engineering MCQs

Practise focused fluid mechanics mechanical engineering questions with marked answers for exam preparation and subject revision.

fluid mechanics mechanical engineering Mcqs
1. Rain drops are spherical because of__________________?
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A. air resistance

B. none of the above

C. viscosity

D. surface tension forces

E. atmospheric pressure

2. An ideal flow of any fluid must fulfill the following____________________?
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A. Continuity equation

B. Newtons law of viscosity

C. Pascal law

D. Newtons law of motion

E. Boundary layer theory

3. True one-dimensional flow occurs when_________________?
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A. the magnitude and direction of the velocity do not change from point to point in the fluid

B. velocity, depth, pressure etc. change from point to point in the fluid flow

C. the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time

D. the direction and magnitude of the veiocity at all points are identical

E. the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane

4. Bernoulli equation deals with the law of conservation of__________________?
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A. work

B. energy

C. force

D. mass

E. momentum

5. A hydraulic press has a ram of 15 cm diameter and plunger of 1.5 cm. It is required to lift a weight of 1 tonne. The force required on plunger is equal to_________________?
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A. 10,000 kg

B. 1000 kg

C. 100 kg

D. 10 kg

E. 1 kg

6. According to the principle of buoyancy a body totally or partially immersed in a fluid will be lifted up by a force equal to_________________?
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A. more than the weight of the body

B. the weight of the body

C. weight of body plus the weight of the fluid displaced hy the body

D. weight of the fluid displaced by the body

E. less than the weight of the body

7. The continuity equation is connected with__________________?
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A. steady/unsteady flow

B. open channel/pipe flow

C. compressibility of fluids

D. viscous/unviscous fluids

E. conservation of mass
8. Normal depth in open channel flow is the depth of flow corresponding to_______________?
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A. uniform flow

B. unsteady flow

C. laminar flow

D. steady flow

E. critical flow

9. The resultant of all normal pressures acts___________________?
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A. at center of pressure

B. at e.g. of body

C. vertically upwards

D. at metacentre

E. vertically downwards

10. The flow in which the particles of a fluid attain such velocities that vary from point to point in magnitude and direction as well as from instant to instant, is known as__________________?
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A. uniform flow

B. steady flow

C. streamline flow

D. turbulent flow

E. one dimensional flow

11. In order that flow takes place between two points in a pipeline, the differential pressure between these points must be more than_______________?
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A. viscosity

B. all of the above

C. none of the above

D. surface friction

E. frictional force

12. A metal with specific gravity of o floating in a fluid of same specific gravity a will____________________?
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A. float over fluid

B. none of the above

C. sink to bottom

D. partly immersed

E. be fully immersed with top surface at fluid surface
13. Which of the following meters is not associated with viscosity____________________?
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A. Say bolt

B. Red wood

C. none of the above

D. Orsat

E. Engler

14. Which of the following manometer has highest sensitivity_________________?
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A. U-tube with mercury

B. displacement type

C. inclined U-tube

D. U-tube with water

E. micro-manometer with water
15. The centre of gravity of the volume of the liquid displaced by an immersed body is called ___________________?
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A. metacentre

B. centroid

C. centre of gravity

D. centre of buoyancy

E. centre of pressure

16. A piece weighing 3 kg in air was found to weigh 2.5 kg when submerged in water. Its specific gravity is_________________?
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A. 1

B. 5

C. 6

D. 7

17. Hydrometer is used to determine____________________?
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A. specific gravity of liquids

B. density

C. specific gravity of gases

D. specific gravity of solids

E. relative humidity

18. For a body floating in a liquid the normal pressure exerted by the liquid acts at ____________________?
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A. all points on the surface of the body

B. all of the above

C. e.g. of the body

D. bottom surface of the body

E. metacentre

19. A body floats in stable equilibrium ____________________?
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A. none of the above

B. when its e.g. is below its center of buoyancy

C. metacentre has nothing to do with position of e.g. for determining stability

D. when the metancentre is above e.g.

E. when its meatcentric height is zero

20. The tendency of a liquid surface to contract is due to the following property_____________?
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A. surface tension

B. viscosity

C. cohesion

D. adhesion

E. elasticity

21. An open vessel of water is accelerated up an inclined plane. The free water surface will__________________?
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A. any one of above is possible

B. none of the above

C. be horizontal

D. make an angle in opposite direction to inclination of inclined plane

E. make an angle in direction of inclination of inclined plane

22. In order to increase sensitivity of U-tube manometer, one leg is usually inclined by angle 9. Sensitivity of inclined tube to sensitivity of U-tube is equal to________________?
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A. sin 9

B. cas 9

C. cos 9

D. sin 9

E. tan 9

23. Metacentre is the point of intersection of _________________________?
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A. vertical upward force through e.g. of body and center line of body

B. none of the above

C. buoyant force and the center line of body

D. all of the above

E. mid point between e.g. and center of buoyancy

24. The flow in which the velocity vector is identical in magnitude and direction at every point, for any given instant, is known as________________?
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A. streamline flow

B. steady flow

C. uniform flow

D. one dimensional flow

E. turbulent flow

25. For measuring flow by a venturimeter, if should be installed in __________________?
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A. inclined line with flow downward

B. horizontal line

C. inclined line with upward flow

D. in any direction and in any location

E. vertical line

26. Pitot tube is used for measurement of_________________?
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A. viscosity

B. flow

C. dsscharge

D. pressure

E. velocity
27. Froude number is significant in__________________?
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A. full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.

B. none of the above

C. supersonics, as with projectile and jet propulsion

D. simultaneous motion through two fluids where there is a surface of dis-continuity, gravity forces, and wave making effect, as with ships hulls

E. all of the above

28. Ratio of inertia force to surface Jension is known as ___________________?
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A. Webers number

B. none of the above

C. Mach number

D. Froude number

E. Reynolds number

29. The units of kinematic viscosity are____________________?
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A. newton-sec per metre

B. none of the above

C. metres2 per sec

D. newton-sec per metre

E. kg sec/metre

30. Which of the following instrument can be used for measuring speed of an aeroplane___________________?
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A. pitot tube

B. hot wire anemometer

C. rotameter

D. Venturimeter

E. Orifice plate

31. Mercury does not wet glass. This is due to property of liquid known as__________________?
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A. adhesion

B. viscosity

C. cohesion

D. surface tension

E. compressibility

32. The property by virtue of which a liquid opposes relative motion between its different layers is called_________________?
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A. co-efficient of viscosity

B. viscosity

C. cohesion

D. osmosis

E. surface tension

33. A piece of metal of specific gravity 7 floats in mercury of specific gravity 13.6. What fraction of its volume is under mercury ?
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A. 0.5

B. 0.515

C. none of the above

D. 0.4

E. 0.5

34. Gradually varied flow is__________________?
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A. steady uniform

B. non-steady uniform

C. steady non-uniform

D. true one-dimensional

E. non-steady non-uniform

35. The pressure in the air space above an oil (sp. gr. 0.8) surface in a tank is 0.1 kg/cm. The pressure at 2.5 m below the oil surface will be __________________?
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A. 3 metres of water column

B. none of the above

C. 4 m of water column

D. 3.5 metres of water column

E. 2 metres of water column

36. At the center line of a pipe flowing under pressure where the velocity gradient is zero, the shear stress will be_________________?
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A. zero

B. minimum

C. could be any value

D. maximum

E. negative value

37. The total energy of each particle at various places in the case of perfect incompres sible fluid flowing in continuous sream__________________?
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A. keeps on increasing

B. may increase/decrease

C. keeps on decreasing

D. unpredictable

E. remains constant
38. In the case of steady flow of a fluid, the acceleration of any fluid particle is________________?
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A. never zero

B. zero

C. variable

D. zero under limiting conditions

E. constant

39. Uniform flow occurs when ___________________?
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A. size and shape of the cross section in a particular length remain constant

B. the flow is streamline

C. size and cross section change uniformly along length

D. flow occurs at constant fate

E. the flow is steady

40. Cavitation will begin when__________________?
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A. the pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid

B. none of the above

C. flow is increased

D. pressure becomes more than critical pressure

E. pressure is increased

41. For hypersonic flow, the Mach number is___________________?
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A. greater than 10

B. greater than unity

C. greater than 4

D. greater than 2

E. unity

42. Increase in pressure at the outer edge of a drum of radius R due to rotation at corad/sec, full of liquid of density p will be___________________?
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A. pco2/?2/2

B. pco2/?2

C. 2pa2R2

D. none of the above

E. pa2R/2

43. Center of pressure compared to e.g. is___________________?
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A. above it

B. below it

C. none of the above

D. at same point

E. above or below depending on area of body

44. Pressure of the order of 10? torr can be measured by__________________?
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A. Pirani Gauge

B. McLeod gauge

C. micro-manometer

D. Bourdon tube

E. ionisastion gauge
45. During the opening of a valve in a pipe line, the flow is_________________?
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A. unsteady

B. free vortex type

C. laminar

D. uniform

E. steady

46. Principle of similitude forms the basis of_________________?
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A. performing acceptance tests

B. designing models so that the result can be converted to prototypes

C. hydraulic designs

D. comparing two identical equipments

E. comparing similarity between design and actual equipment

47. Poise is the unit of________________?
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A. shear stress in fluids

B. surface tension

C. buoyancy

D. capillarity

E. viscosity
48. 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 _________________?
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A. 0.6

B. 0.83

C. 0.4

D. 0.3

E. none of the above

49. Working principle of dead weight pressure gauge tester is based on_______________?
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A. Daltons law of partial pressure

B. Newtons law of viscosity .

C. Pascals law

D. Avogadros hypothesis

E. Second law of thermodynamic

50. In an isothermal atmosphere, the pressure___________________?
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A. varies in the same way as the density

B. decreases linearly with elevation

C. increases exponentially with elevation

D. unpredictable

E. remains constant