NEWTON'S LAWS OF MOTION
Comprehensive JEE Advanced Theory, Constraint Mechanics & Advanced Dynamics
PHYSICS NOTES JEE ADVANCED MECHANICS
1. Frame of Reference & Core Foundations
Before formulating any mechanical equation of motion, an observer must explicitly define the Coordinate
Frame of Reference.
Frame Type Acceleration Condition Applicability of NLM
aframe = 0 (At rest or uniform Newton's Laws hold directly without
Inertial Frame
velocity) modifications.
aframe ≠ 0 (Accelerating or
Non-Inertial Frame Requires introduction of a Pseudo Force.
Rotating)
Pseudo Force (Fpseudo): An apparent force applied to all bodies when observed from an accelerating reference
frame to account for the frame's acceleration.
F̂pseudo = − m · âframe
JEE ADVANCED INSIGHT — VECTOR DIRECTION
The negative sign signifies that the pseudo force vector acting on mass m is strictly opposite to the acceleration
vector of the non-inertial frame (âframe). Its line of action passes through the center of mass of the body.
2. Fundamental Laws of Motion
First Law (Law of Inertia)
Every body continues in its state of rest or uniform motion in a straight line unless compelled to change that
state by an external net force. This law provides the qualitative definition of force as an agent of kinematic
change.
Second Law (Fundamental Law of Mechanics)
The time rate of change of linear momentum (p̂ = m v̂) of a body is directly proportional to and in the direction of
the net external applied force.
F̂net = (d p̂ / dt) = (d(m v̂) / dt)
If mass m remains constant over time:
F̂net = m · (d v̂ / dt) = m · â
Third Law (Action & Reaction)
To every action force, there is always an equal and opposite reaction force.
JEE Advanced Physics • Newton's Laws of Motion Page 1 of 3
Comprehensive JEE Advanced Theory, Constraint Mechanics & Advanced Dynamics
PHYSICS NOTES JEE ADVANCED MECHANICS
1. Frame of Reference & Core Foundations
Before formulating any mechanical equation of motion, an observer must explicitly define the Coordinate
Frame of Reference.
Frame Type Acceleration Condition Applicability of NLM
aframe = 0 (At rest or uniform Newton's Laws hold directly without
Inertial Frame
velocity) modifications.
aframe ≠ 0 (Accelerating or
Non-Inertial Frame Requires introduction of a Pseudo Force.
Rotating)
Pseudo Force (Fpseudo): An apparent force applied to all bodies when observed from an accelerating reference
frame to account for the frame's acceleration.
F̂pseudo = − m · âframe
JEE ADVANCED INSIGHT — VECTOR DIRECTION
The negative sign signifies that the pseudo force vector acting on mass m is strictly opposite to the acceleration
vector of the non-inertial frame (âframe). Its line of action passes through the center of mass of the body.
2. Fundamental Laws of Motion
First Law (Law of Inertia)
Every body continues in its state of rest or uniform motion in a straight line unless compelled to change that
state by an external net force. This law provides the qualitative definition of force as an agent of kinematic
change.
Second Law (Fundamental Law of Mechanics)
The time rate of change of linear momentum (p̂ = m v̂) of a body is directly proportional to and in the direction of
the net external applied force.
F̂net = (d p̂ / dt) = (d(m v̂) / dt)
If mass m remains constant over time:
F̂net = m · (d v̂ / dt) = m · â
Third Law (Action & Reaction)
To every action force, there is always an equal and opposite reaction force.
JEE Advanced Physics • Newton's Laws of Motion Page 1 of 3
