Newton's laws describe how objects move when forces act on them. They are a foundation of classical mechanics and are used to explain motion in everyday life, engineering, sports, vehicles, and astronomy.
First law
An object remains at rest or continues moving at a constant speed in a straight line unless a net external force acts on it. This idea is often called inertia.
Second law
Acceleration depends on force and mass. The relationship is commonly written as F = ma, meaning force equals mass multiplied by acceleration.
Third law
For every action, there is an equal and opposite reaction. When one object pushes another, the second object pushes back with the same size force in the opposite direction.
Why it matters
These laws help explain falling objects, vehicle braking, rocket launches, sports movement, and many engineering calculations.