Newton's first and second laws of motion provide key ingredients for an understanding of force, the principal parameter in Equation 1.
Law 1. An object continues in its initial state of rest or motion with uniform velocity unless it is acted on by an unbalanced, or net external, force. The net force acting on an object, also called the resultant force, is the vector sum of all the forces acting on it (Tipler, 1976).
Mathematically, Law 1 can be expressed as:
Where Fnet represents the net force, and åF represents the vector sum of all of the forces acting on some given object.