First Law of Motion - The Law of Inertia
Newton's First Law of Motion, also known as the Law of Inertia, states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.
Mathematical Expression
When no force acts on an object:
where:
- ΣF is the net force
- v is velocity
- t is time
Key Concepts
- Objects resist changes in their state of motion
- Inertia is proportional to mass
- In the absence of forces, motion continues indefinitely
- Both rest and uniform motion are natural states
Examples in Daily Life
- A book staying at rest on a table
- Passengers moving forward when a bus stops suddenly
- Objects floating in space continuing their motion
- A soccer ball rolling until friction stops it