Who Was Isaac Newton?
Isaac Newton (1643-1727) was one of the greatest scientists ever. He discovered gravity, invented calculus, and wrote the most important physics book ever: Principia. Legend says an apple fell on his head and inspired gravity. (Probably not true, but a good story.)
First Law: Inertia
An object at rest stays at rest, and an object in motion stays in motion, unless acted on by a force. This is called inertia. Your seatbelt keeps you in place when a car stops suddenly — that's inertia. Ice is slippery because very little friction acts on it, so sliding objects keep sliding.
Second Law: F = ma
The force on an object equals its mass times its acceleration. More mass needs more force to move. More force makes things accelerate faster. A bicycle (small mass) speeds up easily. A truck (large mass) needs a huge engine to move.
Third Law: Action-Reaction
For every action, there is an equal and opposite reaction. When you push a wall, the wall pushes back on you with equal force. Rockets work by pushing exhaust gas backward — the gas pushes the rocket forward.
Real Examples
Every sport uses Newton's laws. A soccer ball curves because of spin (air pressure differences). Cars accelerate because the wheels push backward on the road, and the road pushes the car forward. Even walking works: your foot pushes back on the ground, and the ground pushes you forward.