Class 9 Physics Chapter 3 – Dynamics-MCQs-(FBISE)

Description: Practice Class 9 Physics Chapter 3 Dynamics MCQs according to the latest FBISE syllabus. These exam-oriented multiple-choice questions cover force, inertia, momentum, Newton’s laws of motion, friction, and related numerical concepts.

1. Dynamics is the branch of mechanics that studies:

A) Motion without causes
B) Motion and the forces producing it
C) Heat transfer
D) Electric circuits

2. A push or pull acting on a body is called:

A) Force
B) Energy
C) Power
D) Pressure

3. The SI unit of force is:

A) Joule
B) Watt
C) Pascal
D) Newton (N)

4. According to Newton’s First Law, a body at rest remains at rest unless acted upon by:

A) Gravity only
B) Friction only
C) An unbalanced external force
D) Air pressure

5. The tendency of a body to resist any change in its state of rest or motion is called:

A) Momentum
B) Inertia
C) Friction
D) Weight

6. The inertia of an object depends upon its:

A) Mass
B) Shape
C) Volume
D) Colour

7. Newton’s Second Law is commonly expressed as:

A) P=mv
B) W=mg
C) E=mc^2
D) F=ma

8. The SI unit of momentum is:

A) kg
B) \text{kg}\cdot\text{m/s}
C) N
D) J

9. Momentum is calculated using:

A) p=ma
B) p=\frac{m}{v}
C) p=mv
D) p=\frac{v}{m}

10. If the net force acting on an object is zero, the object will:

A) Remain at rest or move with constant velocity
B) Always accelerate
C) Stop immediately
D) Move in a circle

11. Newton’s Third Law states that:

A) F=ma
B) Momentum is conserved
C) Inertia depends on velocity
D) Every action has an equal and opposite reaction

12. Friction always acts:

A) In the direction of motion
B) Opposite to the direction of motion or tendency of motion
C) Vertically upward
D) Towards the centre of Earth

13. Which type of friction acts between two surfaces at rest?

A) Rolling friction
B) Fluid friction
C) Static friction
D) Kinetic friction only

14. A force of 20\,N acts on a mass of 5\,kg. The acceleration produced is:

A) 4\,\text{m/s}^2
B) 5\,\text{m/s}^2
C) 10\,\text{m/s}^2
D) 25\,\text{m/s}^2

15. Which quantity is always conserved in an isolated system during collisions?

A) Speed
B) Force
C) Acceleration
D) Momentum

16. The weight of an object is a:

A) Scalar quantity
B) Force
C) Unit of mass
D) Dimensionless quantity

17. Weight is calculated using the relation:

A) W=mv
B) W=ma
C) W=mg
D) W=\frac{m}{g}

18. Which of the following has the greatest inertia?

A) A truck of mass 5000\,\text{kg}
B) A bicycle of mass 15\,\text{kg}
C) A football of mass 0.45\,\text{kg}
D) A cricket ball of mass 0.16\,\text{kg}

19. The unit 1\,\text{N} is equal to:

A) 1\,\text{kg}\cdot\text{m}
B) 1\,\text{kg}/\text{m}
C) 1\,\text{kg}\cdot\text{m/s}^2
D) 1\,\text{kg}\cdot\text{m/s}

20. If the mass of an object doubles while its velocity remains constant, its momentum will:

A) Remain unchanged
B) Become half
C) Become four times
D) Double

21. Which law explains why passengers move forward when a moving bus stops suddenly?

A) Newton’s Second Law
B) Newton’s First Law
C) Newton’s Third Law
D) Law of Gravitation

22. The force responsible for slowing down a moving object on a rough surface is:

A) Friction
B) Tension
C) Magnetic force
D) Electrostatic force

23. A force of 36\,\text{N} acts on a body of mass 9\,\text{kg}. Its acceleration is:

A) 2\,\text{m/s}^2
B) 3\,\text{m/s}^2
C) 5\,\text{m/s}^2
D) 4\,\text{m/s}^2

24. Which quantity is measured in newtons?

A) Mass
B) Momentum
C) Force
D) Density

25. Rolling friction is generally:

A) Greater than sliding friction
B) Less than sliding friction
C) Equal to sliding friction
D) Infinite

26. A body of mass 4\,\text{kg} moving with velocity 5\,\text{m/s} has momentum:

A) 20\,\text{kg}\cdot\text{m/s}
B) 9\,\text{kg}\cdot\text{m/s}
C) 1.25\,\text{kg}\cdot\text{m/s}
D) 25\,\text{N}

27. Which of the following is a vector quantity?

A) Distance
B) Speed
C) Mass
D) Force

28. The force exerted by the Earth on a body is called its:

A) Momentum
B) Weight
C) Inertia
D) Density

29. If the net force on an object is doubled while its mass remains constant, its acceleration will:

A) Become half
B) Remain unchanged
C) Double
D) Become four times

30. Which law is based on the relationship F=ma?

A) Newton’s Second Law
B) Newton’s First Law
C) Newton’s Third Law
D) Hooke’s Law

31. In SI units, weight is measured in:

A) Kilograms
B) Grams
C) \text{kg}\cdot\text{m/s}
D) Newtons

32. The tendency of a moving body to continue moving in a straight line is due to:

A) Weight
B) Inertia
C) Friction
D) Pressure

33. Which type of friction acts when a book slides across a table?

A) Static friction
B) Rolling friction
C) Sliding friction
D) Fluid friction

34. If m=10\,\text{kg} and g=9.8\,\text{m/s}^2, the weight of the object is:

A) 98\,\text{N}
B) 10\,\text{N}
C) 9.8\,\text{N}
D) 980\,\text{N}

35. Which force opposes the relative motion between two surfaces in contact?

A) Gravitational force
B) Magnetic force
C) Electrostatic force
D) Frictional force

36. A rocket moves upward because:

A) Newton’s First Law
B) Newton’s Third Law
C) Law of Conservation of Energy
D) Hooke’s Law

37. The product of mass and velocity is called:

A) Momentum
B) Force
C) Weight
D) Impulse

38. A force of 50\,\text{N} acts on a body of mass 25\,\text{kg}. The acceleration produced is:

A) 0.5\,\text{m/s}^2
B) 1\,\text{m/s}^2
C) 2\,\text{m/s}^2
D) 5\,\text{m/s}^2

39. The SI unit of mass is:

A) Newton
B) Gram
C) Pound
D) Kilogram (\text{kg})

40. Which of the following reduces friction?

A) Roughening the surfaces
B) Applying lubricants
C) Increasing the load
D) Increasing surface contact

41. The reaction force in Newton’s Third Law acts:

A) On a different body and in the opposite direction
B) On the same body in the same direction
C) Only when the body is at rest
D) Only in space

42. Which property makes it difficult to start moving a heavy object?

A) Density
B) Volume
C) Inertia
D) Temperature

43. The weight of a body on the Moon is:

A) Greater than on Earth
B) Equal to its mass
C) The same as on Earth
D) Less than its weight on Earth

44. A football of mass 0.5\,\text{kg} moving at 8\,\text{m/s} has momentum:

A) 2\,\text{kg}\cdot\text{m/s}
B) 4\,\text{kg}\cdot\text{m/s}
C) 8\,\text{kg}\cdot\text{m/s}
D) 16\,\text{kg}\cdot\text{m/s}

45. Which statement about mass is correct?

A) Mass remains constant regardless of location
B) Mass changes from Earth to Moon
C) Mass is measured in newtons
D) Mass depends on gravity

46. Seat belts in cars are primarily based on:

A) Newton’s Second Law
B) Newton’s Third Law
C) Newton’s First Law (Inertia)
D) Conservation of Energy

47. If the velocity of an object becomes zero, its momentum is:

A) Maximum
B) Zero
C) Equal to its mass
D) Negative

48. Which of the following is an example of rolling friction?

A) A book sliding on a desk
B) A person pushing a box
C) Air acting on a moving car
D) A wheel moving on a road

49. According to Newton’s Second Law, acceleration is directly proportional to:

A) Net force
B) Mass
C) Density
D) Volume

50. Which of the following best defines dynamics?

A) Study of heat and temperature
B) Study of light and sound
C) Study of forces and their effects on motion
D) Study of electrical circuits

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