There are three laws of motion which Newton discovered.
First law:In aninertial frame of reference, an object either remains at rest or continues to move at a constantvelocity,unless acted upon by aforce
Second law:In an inertial frame of reference, the vectorsum of theforces Fon an object is equal to themass mof that object multiplied by theacceleration aof the object:F=ma. (It is assumed here that the massmis constant )
Third law:When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Examples
First law:when a bus suddenly stops the passengers tend to move forward.
Second law:If we throw a heavy ball and a light ball the light ball gets more acceleration.
Third law:if a ball is thrown into a wall it bounces back