Fluid Mechanics Multiple Choice Questions and Answers Pdf

1. The Euler's equation for the motion of liquids is based upon the

assumption that

A. The fluid is non - viscous, homogeneous and incompressible

B. The velocity of flow is uniform over the section

C. The flow is continuous, steady and along the stream line

D. All of the above

Answer: Option D

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2. The Bernoulli's equation is based on the assumption that

A. There is no loss of energy of the liquid flowing

B. The velocity of flow is uniform across any cross-section of the pipe

C. No force except gravity acts on the fluid

D. All of the above

Answer: Option D

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3. The atmospheric pressure at sea level is

A. 103 kN/m

B. 10.3 m of water

C. 760 mm of mercury

D. All of these

Answer: Option D

4. 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: Option D

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Fluid Mechanics Multiple Choice Questions and Answers Pdf

6. The pressure measured with the help of a pressure gauge is called

A. Atmospheric pressure

B. Gauge pressure

C. Absolute pressure

D. Mean pressure

Answer: Option B

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7. A fluid is said to be ideal, if it is

A. Incompressible

B. Viscous and incompressible

C. Inviscous and compressible

D. Inviscous and incompressible 

Answer: Option D

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8. The dynamic viscosity of the liquid __________ with rise in temperature.

A. Remain unaffected

B. Increases

C. Decreases

D. None of these

Answer: Option C

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9. The dynamic viscosity of gases __________ with rise in temperature.

A. Remain unaffected

B. Increases

C. Decreases

D. None of these

Answer: Option B

10. The overall efficiency of a reaction turbine is the ratio of

A. Power produced by the turbine to the energy actually supplied by the turbine

B. Actual work available at the turbine to the energy imparted to the wheel

C. Work-done on the wheel to the energy (or head of water) actually supplied to the

turbine

D. None of the above

Answer: Option A

Fluid Mechanics Multiple Choice Questions and Answers Pdf

18. One cubic metre of water weighs

A. 100 liters

B. 250 liters

C. 500 liters

D. 1000 liters

Answer: Option D

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19. According to fan laws, for fans having constant wheel diameter, the pressure varies

A. Directly as fan speed

B. Square of fan speed

C. Cube of fan speed

D. Square root of fan speed

Answer: Option B

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20. A turbine is required to develop 1500 kW at 300 r.p.m. under a head of 150 m. Which of the following turbine should be used?

A. Pelton wheel with one nozzle

B. Pelton wheel with two or more nozzles

C. Kaplan turbine

D. Francis turbine

Answer: Option A

21. The specific speed of turbine is defined as the speed of a unit

A. Of such a size that it delivers unit discharge at unit head

B. Of such a size that it delivers unit discharge at unit power

C. Of such a size that it requires unit power per unit head

D. Of such a size that it produces unit horse power with unit head

Answer: Option D

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24. A weir is said to be narrow-crested weir, if the width of the crest of the weir is __________ half the height of water above the weir crest.

A. Equal to

B. Less than

C. More than

D. None of these

Answer: Option B

25. A weir is said to be broad crested weir, if the width of the crest of the weir is ________ half the height of water above the weir crest.

A. Equal to

B. Less than

C. More than

D. None of these

Answer: Option C

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Fluid Mechanics Multiple Choice Questions and Answers Pdf

26. Braking jet in an impulse turbine is used

A. To break the jet of water

B. To bring the runner to rest in a short time

C. To change the direction of runner

D. None of these

Answer: Option B

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27. Rotameter is a device used to measure

A. Absolute pressure

B. Velocity of fluid

C. Flow

D. Rotation

Answer: Option C

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28. In an internal mouthpiece, the absolute pressure head at vena contracta is __________ the atmospheric pressure head by an amount equal to height of the liquid above the vena contracta.

A. Less than

B. More than

C. Equal to

D. None of these

Answer: Option A

29. In an external mouthpiece, the absolute pressure head at vena contracta is __________ the atmospheric pressure head by an amount equal to 0.89 times the height of the liquid, above the vena contracta.

A. Less than

B. More than

C. Equal to

D. None of these

Answer: Option A

30. Choose the wrong statement

A. Fluids are capable of flowing

B. Fluids conform to the shape of the containing vessels

C. When in equilibrium, fluids cannot sustain tangential forces

D. When in equilibrium, fluids can sustain shear forces

Answer: Option D

Fluid Mechanics Multiple Choice Questions and Answers Pdf

31. Choose the wrong statement

A. Viscosity of a fluid is that property which determines the amount of its resistance to a shearing force

B. Viscosity is due primarily to interaction between fluid molecules

C. Viscosity of liquids decreases with increase in temperature

D. Viscosity of liquids is appreciably affected by change in pressure

Answer: Option D

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32. 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: Option D

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33. Choose the wrong statement

A. Any weight, floating or immersed in a liquid, is acted upon by a buoyant force

B. Buoyant force is equal to the weight of the liquid displaced

C. The point through which buoyant force acts, is called the center of buoyancy

D. Center of buoyancy is located above the center of gravity of the displaced liquid

Answer: Option D

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34. Select the wrong statement

A. An equivalent pipe is treated as an ordinary pipe for all calculations

B. The length of an equivalent pipe is equal to that of a compound pipe

C. The discharge through an equivalent pipe is equal to that of a compound pipe

D. The diameter of an equivalent pipe is equal to that of a compound pipe

Answer: Option D

35. 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: Option D

Fluid Mechanics Multiple Choice Questions and Answers Pdf

41. 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: Option D

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42. 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: Option B

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43. The resultant upward pressure of the fluid on an immersed body due to its tendency to uplift the submerged body is called

A. Up-thrust

B. Reaction

C. Buoyancy

D. Metacentre

Answer: Option C

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44. A ship whose hull length is 100 m is to travel at 10 m/sec. For dynamic similarity, at what velocity should a 1:25 model be towed through water?

A. 10 m/sec

B. 25 m/sec

C. 2 m/sec

D. 50 m/sec

Answer: Option C

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45. A pitot tube is used to measure the

A. Velocity of flow at the required point in a pipe

B. Pressure difference between two points in a pipe

C. Total pressure of liquid flowing in a pipe

D. Discharge through a pipe

Answer: Option A

Fluid Mechanics Multiple Choice Questions and Answers Pdf