Fluid Mechanics (Practice Test MCQs)

50 Score: 0 Attempted: 0/50

1. What is the unit of dynamic viscosity in SI units?
(A) Pa·s
(B) N·s/m²
(C) kg/m·s
(D) All of the above

2. Which law states that pressure at a point in a fluid is the same in all directions?
(A) Pascal’s Law
(B) Bernoulli’s Principle
(C) Archimedes’ Principle
(D) Newton’s Law

3. The density of water at 4°C is approximately:
(A) 1000 kg/m³
(B) 997 kg/m³
(C) 1030 kg/m³
(D) 980 kg/m³

4. Continuity equation is based on the principle of:
(A) Conservation of energy
(B) Conservation of momentum
(C) Conservation of mass
(D) Conservation of volume

5. Which instrument is used to measure the flow of fluids?
(A) Barometer
(B) Manometer
(C) Venturimeter
(D) Hygrometer

6. Which property of a fluid resists the relative motion between adjacent layers?
(A) Density
(B) Viscosity
(C) Surface tension
(D) Capillarity

7. The pressure intensity in a static fluid varies with:
(A) Volume
(B) Temperature
(C) Depth
(D) Density only

8. Bernoulli’s equation is applicable to:
(A) Viscous flow only
(B) Non-viscous, incompressible flow
(C) Compressible flow only
(D) All types of flow

9. The angle of contact in a capillary tube depends on:
(A) Diameter of the tube
(B) Nature of the liquid and the solid
(C) Density of the liquid
(D) Temperature only

10. The buoyant force is equal to:
(A) Weight of the body
(B) Weight of displaced fluid
(C) Weight of the immersed portion
(D) Volume of the body

11. What is the Reynolds number for laminar flow in a pipe?
(A) Re < 2000
(B) Re = 2000–4000
(C) Re > 4000
(D) Re < 400

12. The unit of kinematic viscosity is:
(A) N·s/m²
(B) m²/s
(C) kg/m·s
(D) Pa·m²

13. Streamline flow is characterized by:
(A) High velocity
(B) Low pressure
(C) No mixing of fluid particles
(D) Large eddies

14. The metacentric height is a measure of:
(A) Stability of a floating body
(B) Density of a fluid
(C) Pressure at a point
(D) Surface tension force

15. Cavitation in pumps occurs when:
(A) Velocity decreases
(B) Pressure falls below vapor pressure
(C) Temperature increases
(D) Discharge reduces

16. Which type of flow has constant velocity at a point with time?
(A) Steady flow
(B) Unsteady flow
(C) Compressible flow
(D) Rotational flow

17. The center of pressure is located:
(A) Above the centroid
(B) At the centroid
(C) Below the centroid
(D) Cannot be determined

18. Surface tension is caused by:
(A) Viscosity
(B) Cohesion between molecules
(C) Adhesion between molecules
(D) Capillary rise

19. The pressure in a liquid at rest increases:
(A) Upward
(B) Downward
(C) Sideways
(D) In all directions

20. In a siphon, the pressure at the highest point is:
(A) Greater than atmospheric pressure
(B) Equal to atmospheric pressure
(C) Less than atmospheric pressure
(D) Always zero

21. A piezometer measures:
(A) Total pressure
(B) Static pressure head
(C) Dynamic pressure
(D) Velocity head

22. The hydraulic gradient line (HGL) is always:
(A) Above the energy line
(B) Below the energy line by velocity head
(C) Below the piezometric head
(D) Equal to datum head

23. The discharge through an orifice is given by:
(A) Q = A·V
(B) Q = Cd·A·√(2gh)
(C) Q = Cv·g·h
(D) Q = ρ·g·h

24. Which flow has velocity changing with respect to time?
(A) Steady flow
(B) Unsteady flow
(C) Streamline flow
(D) Laminar flow

25. The ratio of inertia force to viscous force is:
(A) Mach number
(B) Reynolds number
(C) Froude number
(D) Euler number

26. In laminar flow, the velocity distribution is:
(A) Parabolic
(B) Linear
(C) Hyperbolic
(D) Constant

27. What is the main cause of fluid friction?
(A) Density
(B) Viscosity
(C) Temperature
(D) Turbulence

28. The unit of surface tension is:
(A) N/m²
(B) N/m
(C) N·m
(D) kg/m²

29. Archimedes’ principle is used in:
(A) Measuring density of solids and liquids
(B) Measuring pressure in pipes
(C) Determining viscosity
(D) Calculating flow through orifices

30. The loss of energy due to sudden enlargement in a pipe is termed as:
(A) Frictional loss
(B) Minor loss
(C) Hydraulic loss
(D) Turbulent loss

31. What is the specific gravity of a fluid with density 800 kg/m³?
(A) 0.8
(B) 1.2
(C) 0.88
(D) 1.25

32. The head loss due to friction is calculated using:
(A) Bernoulli’s equation
(B) Darcy–Weisbach equation
(C) Archimedes’ principle
(D) Continuity equation

33. Which device measures flow velocity using pressure difference?
(A) Manometer
(B) Orifice meter
(C) Anemometer
(D) Rotameter

34. The center of buoyancy is the:
(A) Geometric center of the object
(B) Center of gravity of the displaced fluid
(C) Lowest point of the submerged body
(D) Center of mass of the fluid

35. For a floating body, the weight acts:
(A) Above the metacenter
(B) At the metacenter
(C) Through the center of gravity
(D) Below the center of buoyancy

36. Which of the following is an example of ideal fluid?
(A) Air
(B) Water
(C) Oil
(D) None (ideal fluids are hypothetical)

37. Mach number is the ratio of:
(A) Flow velocity to gravitational force
(B) Flow velocity to sound velocity
(C) Flow velocity to density
(D) Flow velocity to kinematic viscosity

38. Froude number represents the ratio of:
(A) Inertia force to gravity force
(B) Inertia force to viscous force
(C) Inertia force to surface tension
(D) Viscous force to gravity force

39. The unit of pressure in the SI system is:
(A) N
(B) N/m
(C) N/m²
(D) kg/m³

40. The phenomenon of rise or fall of a liquid in a capillary tube is due to:
(A) Surface tension
(B) Viscosity
(C) Pressure difference
(D) Density variation

41. In turbulent flow, the head loss varies:
(A) Directly with velocity
(B) Directly with velocity squared
(C) Inversely with velocity
(D) Independent of velocity

42. The dimension of kinematic viscosity is:
(A) L²/T
(B) L/T
(C) L³/T
(D) L/T²

43. The term “slug flow” refers to:
(A) Steady flow in a pipe
(B) Unsteady flow with gas-liquid mixture
(C) Laminar flow with low pressure
(D) Flow in an open channel

44. The Hagen–Poiseuille equation is used for:
(A) Turbulent flow
(B) Laminar flow in pipes
(C) Compressible flow
(D) Free surface flow

45. The coefficient of discharge (Cd) is always:
(A) Greater than 1
(B) Equal to 1
(C) Less than 1
(D) Zero

46. Manometric fluids are used to measure:
(A) Only atmospheric pressure
(B) Only dynamic pressure
(C) Difference of pressure between two points
(D) Volume flow rate

47. The flow in a river is an example of:
(A) Steady, compressible flow
(B) Steady, incompressible flow
(C) Unsteady, compressible flow
(D) Rotational flow

48. Which type of pump operates based on displacement of fluid?
(A) Centrifugal pump
(B) Reciprocating pump
(C) Jet pump
(D) Axial flow pump

49. What is the term for pressure lower than atmospheric pressure?
(A) Static pressure
(B) Vacuum pressure
(C) Absolute pressure
(D) Dynamic pressure

50. The primary cause of turbulence is:
(A) High fluid density
(B) Low velocity
(C) High flow velocity and obstacles
(D) Surface tension

Fluid Mechanics (Practice Test MCQs)

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