Motion for All SSC Exams Start Now!!

What Causes Motion?

  1. Motion is caused due to force.

Concept of force

  • The SI unit of force is the Newton (N).
  • Forces can be balanced (net force = 0, no acceleration) or unbalanced (net force ≠ 0, causes acceleration).
  • Forces can be contact (e.g., frictional force) or non-contact (e.g., gravitational force).
  • Forces can be conservative (work done is independent of the path) or non-conservative (work done depends on the path).

Laws of Motion:

  • First Law of Motion (Inertia): An object remains at rest or in motion at a constant velocity unless acted upon by an external force.
    • Example: A person sitting in a moving car is pushed forward when the car stops abruptly.
  • Second Law of Motion (Momentum): The rate of change of momentum is proportional to the applied force and occurs in the direction of the force.
    • Example: A truck has more momentum than a bullet bike if its mass is greater than the bike’s velocity.

Third Law of Motion: For every action, there is an equal and opposite reaction.

  • Example: A rocket expels gas downwards, and as a reaction, it moves upwards.

Conservation of Momentum:

  • The total momentum before and after a collision is conserved.

One-liners (MCQs):

  • The range of weak nuclear force is of the order of 10^-18 m.
  • The force of friction always opposes the applied forces.
  • The force of the Earth’s gravity on every kilogram is about 10 N.
  • Gravitational force is an example of an “action at a distance” force.
  • Once a satellite is launched into orbit, the only force governing its motion is the force of gravity.
  • The SI unit of Electrostatic force is Coulomb (C).
  • Torque is the measure of force that can cause an object to rotate about an axis.


1 / 7

What is torque?


2 / 7

What is the SI unit of Electrostatic force?


3 / 7

What force governs the motion of a satellite once it is launched into orbit?


4 / 7

Which of the following is an example of an “action at a distance” force?


5 / 7

What is the range of the weak nuclear force?


6 / 7

What does the force of friction do?


7 / 7

What is the force of the Earth’s gravity on every kilogram?


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The average score is 82%








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