Newton's three laws of motion · Pulse Beat

1. Inertia. An object keeps doing what it is doing, staying still or moving in a straight line at a steady speed, unless a net force acts on it.

1. Inertia. An object keeps doing what it is doing, staying still or moving in a straight line at a steady speed, unless a net force acts on it.

2. F = m × a. The net force on an object equals its mass times its acceleration. The same push speeds up a light cart more than a heavy one. Force is measured in newtons: 1 N accelerates 1 kg by 1 m/s².

3. Action and reaction. When one object pushes on another, the second pushes back on the first with an equal and opposite force. A rocket pushes gas backward, and the gas pushes the rocket forward.

These describe everyday motion very well. They stop being accurate at speeds near the speed of light and at atomic scales, where relativity and quantum mechanics take over.