Summary Master The NCERT Physics Vol-1 (E) - PHYSICS

Chapter 4: Laws of Motion




1. Introduction to Laws of Motion

- Laws of motion describe the relationship between the force applied to an object and its motion.

- These laws were formulated by Sir Isaac Newton.



2. Newton's Laws of Motion



First Law (Law of Inertia)

- A body remains at rest or in uniform motion unless acted upon by an external force.

- Inertia: The tendency of an object to resist a change in its state of motion.

- Types of Inertia:

1. Inertia of Rest: A body at rest remains at rest (e.g., dust falling off a carpet when beaten).

2. Inertia of Motion: A moving body continues to move (e.g., passengers moving forward when a

bus suddenly stops).

3. Inertia of Direction: A body continues moving in the same direction unless acted upon (e.g., a

passenger moving sideways when a car takes a sharp turn).



Second Law (Law of Acceleration)

- The rate of change of momentum of a body is directly proportional to the applied force and occurs

in the direction of force.

- Mathematically: F = ma

where,

F = Force (N), m = Mass (kg), a = Acceleration (m/s^2)

- Momentum: p = mv