Some bodies are at rest and some are in motion. A body needs a 'push' or 'pull' to move, to come to rest or to change its velocity – this push or pull is called force. This unit studies the cause of motion using the three laws of motion proposed by Sir Isaac Newton, along with inertia, momentum, torque, impulse, gravitation, mass and weight, apparent weight and weightlessness.
1. Mechanics and Its Branches
Mechanics is the branch of physics that deals with the effect of force on bodies. It is divided into two branches: statics and dynamics. Dynamics is further divided into kinematics and kinetics.
| Branch | What it deals with |
|---|---|
| Statics | Bodies which are at rest under the action of forces |
| Dynamics | Moving bodies under the action of forces |
| Kinematics (part of dynamics) | Motion of bodies without considering the cause of motion |
| Kinetics (part of dynamics) | Motion of bodies considering the cause of motion |