📘 FLUID MECHANICS & HYDRAULIC MACHINES – 50 MCQs

🟢 Q1. What is fluid mechanics?

A) Study of solids

B) Study of gases only

C) Study of fluids at rest and motion

D) Study of heat

✅ Answer: C

Explanation: Fluid mechanics deals with both fluid at rest (statics) and in motion (dynamics).

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🟢 Q2. Reynolds number represents:

A) Pressure ratio

B) Inertia force / viscous force

C) Velocity ratio

D) Density ratio

✅ Answer: B

Explanation: Reynolds number determines flow type (laminar/turbulent).

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🟢 Q3. Laminar flow occurs when Reynolds number is:

A) > 4000

B) < 2000

C) 2000–4000

D) None

✅ Answer: B

Explanation: Flow is laminar below 2000 in pipes.

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🟢 Q4. Unit of viscosity is:

A) Pascal-second

B) Newton

C) Joule

D) Watt

✅ Answer: A

Explanation: Dynamic viscosity unit = Pa·s

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🟢 Q5. Pressure in fluid at rest acts:

A) Only downward

B) Only upward

C) In all directions

D) Horizontal

✅ Answer: C

Explanation: Fluid pressure acts equally in all directions.

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🟢 Q6. Bernoulli’s equation is based on:

A) Momentum

B) Energy conservation

C) Mass

D) Heat

✅ Answer: B

Explanation: It represents conservation of energy in fluid flow.

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🟢 Q7. Continuity equation represents:

A) Energy

B) Momentum

C) Mass conservation

D) Pressure

✅ Answer: C

Explanation: It ensures mass flow rate remains constant.

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🟢 Q8. Pitot tube measures:

A) Pressure

B) Velocity

C) Temperature

D) Density

✅ Answer: B

Explanation: Pitot tube measures flow velocity.

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🟢 Q9. Hydraulic machines convert:

A) Electrical → Heat

B) Hydraulic → Mechanical

C) Mechanical → Heat

D) Heat → Electrical

✅ Answer: B

Explanation: They convert fluid energy into mechanical energy.

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🟢 Q10. Example of dynamic fluid study:

A) Fluid at rest

B) Flow in pipe

C) Static tank

D) Pressure measurement

✅ Answer: B

Explanation: Fluid motion is studied in dynamics.

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🔷 (Continue same pattern — I will give all 50 below compact but complete)

🟢 Q11. Density unit:

A) kg/m³ ✅

B) N/m²

C) m/s

D) kg

Explanation: Mass per unit volume

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🟢 Q12. Specific gravity is:

A) Ratio of density

B) Pressure

C) Velocity

D) Area

✅ Answer: A

🟢 Q13. Flow with constant discharge:

A) Unsteady

B) Steady ✅

C) Turbulent

D) Compressible

🟢 Q14. Surface tension acts:

A) Inside liquid

B) On surface ✅

C) On bottom

D) On walls

🟢 Q15. Pascal law states:

A) Pressure varies

B) Pressure same in all directions ✅

C) Velocity constant

D) Flow constant

🟢 Q16. Cavitation occurs due to:

A) High pressure

B) Low pressure below vapor pressure ✅

C) High velocity

D) Heat

🟢 Q17. Pump converts:

A) Mechanical → Hydraulic ✅

B) Hydraulic → Mechanical

C) Electrical → Mechanical

D) Heat

🟢 Q18. Turbine converts:

A) Mechanical → Electrical

B) Hydraulic → Mechanical ✅

C) Heat → Work

D) None

🟢 Q19. Specific speed relates:

A) Flow

B) Pump performance ✅

C) Density

D) Pressure

🟢 Q20. Head loss due to friction:

A) Minor loss

B) Major loss ✅

C) Energy gain

D) None

🟢 Q21. Venturimeter measures:

A) Pressure

B) Flow rate ✅

C) Velocity

D) Temperature

🟢 Q22. Manometer measures:

A) Velocity

B) Pressure difference ✅

C) Flow

D) Density

🟢 Q23. Streamline flow means:

A) Random

B) Smooth paths ✅

C) Chaotic

D) Rotational

🟢 Q24. Hydraulic efficiency:

A) Power ratio ✅

B) Velocity ratio

C) Pressure ratio

D) Density ratio

🟢 Q25. Froude number compares:

A) Inertia & gravity forces ✅

B) Viscous & pressure

C) Heat & flow

D) None

🟢 Q26. Boundary layer occurs:

A) Inside fluid

B) Near surface ✅

C) Outside flow

D) In vacuum

🟢 Q27. Turbulent flow is:

A) Smooth

B) Random motion ✅

C) Linear

D) Static

🟢 Q28. Kinematic viscosity unit:

A) m²/s ✅

B) Ns/m²

C) kg/m³

D) Pa

🟢 Q29. Hydraulic radius:

A) Area / perimeter ✅

B) Velocity ratio

C) Pressure

D) Density

🟢 Q30. Jet impact force:

A) Momentum change ✅

B) Pressure change

C) Heat

D) Density

🟢 Q31. Centrifugal pump works on:

A) Centrifugal force ✅

B) Gravity

C) Pressure

D) Heat

🟢 Q32. Reciprocating pump:

A) Continuous flow

B) Intermittent flow ✅

C) No flow

D) Turbulent

🟢 Q33. Efficiency of pump depends on:

A) Head & discharge ✅

B) Temperature

C) Density

D) Color

🟢 Q34. Hydraulic jump occurs:

A) High velocity

B) Sudden depth rise ✅

C) Pressure drop

D) No flow

🟢 Q35. Ideal fluid has:

A) No viscosity ✅

B) High viscosity

C) Density

D) Pressure

🟢 Q36. Flow net used for:

A) Velocity

B) Flow visualization ✅

C) Pressure

D) Heat

🟢 Q37. Specific weight:

A) Weight/volume ✅

B) Mass/area

C) Pressure

D) Velocity

🟢 Q38. Hydrostatic pressure depends on:

A) Depth ✅

B) Velocity

C) Temperature

D) Area

🟢 Q39. Viscosity resists:

A) Flow ✅

B) Pressure

C) Heat

D) Gravity

🟢 Q40. Head loss proportional to:

A) Velocity² ✅

B) Velocity

C) Pressure

D) Density

🟢 Q41. Pelton turbine:

A) Reaction

B) Impulse ✅

C) Axial

D) Radial

🟢 Q42. Francis turbine:

A) Impulse

B) Reaction ✅

C) Radial

D) None

🟢 Q43. Kaplan turbine:

A) Radial

B) Axial flow ✅

C) Mixed

D) None

🟢 Q44. Cavitation damages:

A) Pump blades ✅

B) Pipe

C) Tank

D) Valve

🟢 Q45. Discharge formula:

A) Q = AV ✅

B) Q = V/A

C) Q = P/A

D) None

🟢 Q46. Critical velocity depends on:

A) Viscosity & density ✅

B) Area

C) Pressure

D) Heat

🟢 Q47. Pressure head:

A) P/ρg ✅

B) V²

C) Q

D) None

🟢 Q48. Flow measurement device:

A) Venturimeter ✅

B) Thermometer

C) Barometer

D) None

🟢 Q49. Pump head:

A) Energy per unit weight ✅

B) Velocity

C) Density

D) Pressure

🟢 Q50. Hydraulic machines mainly use:

A) Air

B) Water ✅

C) Oil

D) Steam

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