fluid mechanics MCQs – Page 2

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

fluid mechanics Mcqs
21. The distance y from pipe boundary, at which the point velocity is equal to average velocity for turbulent flow, is________________?
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A. 0.577 R

B. 0.223 R

C. 0.423 R

D. 0.707 R

22. The speed of a pressure wave through a pipe depends upon________________?
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A. the bulk modulus for the fluid

B. the viscosity of fluid

C. the length of pipe

D. the original head

23. In which of the following the friction drag is generally larger than pressure drag?
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A. a sphere

B. an airfoil

C. a circular disc or plate held normal to flow

D. a cylinder

24. The value of friction factor f for smooth pipes for Reynolds number 106 is approximately equal to________________?
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A. 0.1

B. 0.01

C. 0.0001

D. 0.001

25. In series-pipe problems_______________?
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A. the discharge is same through each pipe

B. a trial solution is not necessary

C. the head loss is same through each pipe

D. the discharge through each pipe is added to obtain total discharge

26. Pascal-second is the unit of______________?
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A. pressure

B. dynamic viscosity

C. kinematic viscosity

D. surface tension

27. An ideal fluid is_______________?
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A. frictionless and incompressible

B. one which obeys Newtons law of viscosity

C. very viscous

D. frictionless and compressible

28. If the weight of a body immersed in a fluid exceeds the buoyant force, then the body will________________?
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A. float

B. rise until its weight equals the buoyant force

C. none of the above

D. tend to move downward and it may finally sink
29. The viscosity of a gas_______________?
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A. increases with increase in temperature

B. is independent of pressure for very high pressure intensities

C. decreases with increase in temperature

D. is independent of temperature

30. The discharge over a broad crested weir is maximum when the depth of flow is_______________?
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A. 2 H/3

B. H/3

C. H/2

D. 2 H/5

31. When a liquid rotates at a constant angular velocity about a vertical axis as a rigid body, the pressure intensity varies________________?
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A. inversely as the square of the radial distance

B. as the square of the radial distance

C. inversely as the radial distance

D. linearly with radial distance

32. The unit of kinematic viscosity is_______________?
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A. dyne-sec/cm2

B. cm2/sec

C. gm/cm2-sec

D. gm/cm-sec2

33. A rectangular block 2 m long, 1 m wide and 1 m deep floats in water, the depth of immersion being 0.5 m. If water weighs 10 kN/m3, then the weight of the block is________________?
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A. 15 kN

B. 5kN

C. lOkN

D. 20 kN

34. Coefficient of velocity of venturimeter_________________?
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A. none of the above

B. is equal to the coefficient of discharge of venturimeter

C. is independent of Reynolds number

D. decreases with higher Reynolds number

35. When an ideal fluid flows past a sphere________________?
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A. lowest pressure intensity occurs at rear stagnation point

B. total drag is zero

C. lowest pressure intensity occurs at front stagnation point

D. highest intensity of pressure occurs around the circumference at right angles to flow

36. The motion of air mass in a tornado is a________________?
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A. forced vortex at center and free vortex outside

B. free vortex at center and forced vortex outside

C. free vortex motion

D. forced vortex motion

37. The position of center of pressure on a plane surface immersed vertically in a static mass of fluid is______________?
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A. always above the centroid of the area

B. none of the above

C. always below the centroid of the area

D. at the centroid of the submerged area

38. The distance from pipe boundary, at which the turbulent shear stress is one-third die wall shear stress, is_______________?
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A. 2/3 R

B. 1/3 R

C. 1/2 R

D. 3/4R

39. With the same cross-sectional area and immersed in same turbulent flow, the largest total drag will be on__________________?
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A. a circular disc of plate held normal to flow

B. a cylinder

C. a streamlined body

D. a sphere

40. A vertical rectangular plane surface is submerged in water such that its top and bottom surfaces are 1.5 m and 6.0 m res-pectively below the free surface. The position of center of pressure below the free surface will be at a distance of________________?
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A. 4.2m

B. 3.75 m

C. 4.5m

D. 4.0 m