Newton's laws of motion are three physical laws that together have laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to said forces. Can be summarized as:
1) First law: When viewed in in inertial sense, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force. For example, a bike once set into motion does not stop without the application of friction forces.
2) Second law: F = ma. The vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration vector a of the object.
3) 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.
