Physics Fluid Dynamics Online Mcqs Test

Mustansar KhanLast Updated: October 13, 2025

Important Fluid Dynamics Question and Answer

Total Questions:	49
Time Allowed:	25 Minutes
Total Marks:	49
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	Physics Test ECAT Test MDCAT Test FPSC/PPSC/SPSC/KPPSC/BPSC/AJKPSC/NTS Physics Interview Question Answer

Physics Fluid Dynamics Practice Test Online With Explanation

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1. Which of the following increases both buoyant force and drag?

Increased mass

Decreased density

Increased color

Increased volume

2. Which term refers to the force opposing motion through water?

Friction

Tension

Fluid drag

Compression

3. Which of the following best describes fluid drag?

Force of gravity in fluid

Resistance force exerted by fluid

Upthrust acting downward

Attractive force in liquids

4. What does ‘ρ’ represent in Stokes' Law?

Fluid density

Object radius

Density of the object

Viscosity

5. Which of the following objects will have the lowest terminal velocity?

Smooth steel ball

Parachute

Iron rod

Water droplet

6. How is terminal velocity useful in designing parachutes?

Helps reduce upward motion

Helps control and limit descent speed

Helps increase falling speed

Eliminates the effect of gravity

7. At terminal velocity, which of the following is true?

Speed keeps increasing

Acceleration is zero

Acceleration is constant

Speed is zero

8. What causes a skydiver to reach terminal velocity?

Air resistance increasing with speed

Lack of friction

Constant acceleration

Gravity only

9. If a skydiver opens their parachute, what happens to their terminal velocity?

Decreases

Stays the same

Increases

Becomes zero

10. Terminal velocity occurs when:

Drag force = 0

Drag force = weight

No force acts on the object

Drag force > weight

11. Which quantity becomes constant at terminal velocity?

Velocity

Momentum

Mass

Acceleration

12. Why does a feather fall slower than a stone?

Stronger gravity

Higher drag to weight ratio

More mass

Less weight

13. How does fluid viscosity affect terminal velocity?

Decreases it

Has no effect

Increases it

Makes it infinite

14. How does an object behave in fluid if drag force is less than weight?

It comes to rest

It accelerates downward

It floats

It sinks with constant velocity

15. Which of these equations best expresses terminal velocity (vₜ) under Stokes’ law for a sphere?

vₜ = (rη)/(2ρg)

vₜ = ηg/ρ

vₜ = mg/r²

vₜ = (2r²g(ρ - σ)) / 9η

16. What happens to acceleration after terminal velocity is reached?

Decreases

Becomes zero

Becomes negative

Increases

17. How can terminal velocity be increased?

Increase fluid density

Decrease object mass

Increase surface area

Decrease surface area

18. The drag force acting on an object is caused by:

Buoyancy

The object’s mass

The relative motion between the object and fluid

Gravitational field

19. What is the SI unit of drag force?

Pascal

Joule

Watt

Newton

20. What happens to the net force on an object at terminal velocity?

It equals the weight

It becomes zero

It increases linearly

It becomes maximum

21. What is the shape of an object that experiences minimum drag?

Irregular

Flat

Spherical

Streamlined

22. Which fluid property affects drag the most?

Density

Odor

Transparency

Color

23. Which of the following is not a factor in determining fluid drag?

Speed of object

Shape of object

Color of object

Density of fluid

24. Which object would reach terminal velocity the quickest when dropped from the same height?

Wooden cube

Steel ball

Crumpled paper

Feather

25. Which of the following factors increases drag on a moving object?

Increasing fluid density

Increasing surface smoothness

Decreasing speed

Reducing area

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26. If mass increases but surface area remains constant, terminal velocity:

Decreases

Becomes zero

Stays constant

Increases

27. What is the terminal velocity of an object dependent on?

Object’s shape, size, and mass

Volume only

Color and texture

Sound produced

28. Which of the following affects terminal velocity?

Temperature of the object

Color of the object

Volume only

Shape and surface area

29. Which object is most affected by air resistance?

Glass marble

Flat sheet of paper

Plastic ball

Iron nail

30. What is drag?

Centripetal force

Downward force in a solid

Frictional force exerted by fluids

Upward force acting in vacuum

31. In which situation is fluid drag negligible?

Rain falling

Stone in water

Vacuum

Skydiver falling

32. What does a higher viscosity fluid mean for an object falling through it?

No change in velocity

Greater resistance

Constant acceleration

Less resistance

33. Which of the following is an incorrect statement about fluid drag?

It is absent in a vacuum

It increases when mass increases

It depends on velocity

It always acts opposite to motion

34. In which fluid will a ball fall with the lowest terminal velocity?

Oil

Honey

Water

Air

35. Which term describes motion at constant velocity through a fluid?

Free motion

Terminal motion

Accelerated motion

Uniform motion

36. What is terminal velocity?

The speed at which pressure becomes zero

The highest speed of a car

The maximum constant speed of a falling object in a fluid

The speed of sound

37. What is the relation between drag force and velocity for a spherical object in laminar flow?

Independent of velocity

Inversely proportional to velocity

Proportional to square of velocity

Directly proportional to velocity

38. What happens to terminal velocity in a vacuum?

Decreases

Becomes infinite

Increases

Does not exist

39. At what point does an object stop accelerating during free fall?

When net force becomes zero

At maximum height

Just before hitting the ground

At the beginning of fall

40. The faster an object moves through a fluid, the:

More the lift

Lower the pressure

Greater the drag

Less the drag

41. Which force balances weight at terminal velocity?

Normal force

Electromagnetic force

Drag force

Centrifugal force

42. The net force on an object falling at terminal velocity is:

Negative

Zero

Equal to weight

Equal to air resistance

43. How does terminal velocity vary with mass?

Constant

Directly proportional

Inversely proportional

Not related

44. Which of the following best represents a real-world example of terminal velocity?

A stone thrown upward

A parachutist falling at constant speed

A car accelerating on a highway

A ball rolling on a table

45. Which law explains the viscous drag on small spheres in a fluid?

Bernoulli’s Principle

Newton’s Second Law

Archimedes' Law

Stokes’ Law

46. The direction of drag force is always:

Opposite to motion

Along velocity

Perpendicular to motion

Downward

47. What happens to drag force as velocity increases in turbulent flow?

Increases with square of velocity

Decreases

Remains constant

Becomes zero

48. Which force opposes the motion of an object moving through a fluid?

Gravitational force

Normal force

Magnetic force

Drag force

49. Which factor will decrease the terminal velocity of a falling object?

Increasing gravitational acceleration

Increasing its surface area

Decreasing fluid viscosity

Increasing its mass

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Mustansar KhanLast Updated: October 13, 2025

Important Fluid Dynamics Question and Answer

Physics Fluid Dynamics Practice Test Online With Explanation

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