Force
In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.
Net force
A force is known as a bound vector—which means it has a direction and magnitude and a point of application. A convenient way to define a force is by a line segment from a point "A" to a point "B". If we denote the coordinates of these points as A=(A, A, A) and B=(B, B, B), then the force vector applied at "A" is given by
The length of the vector B-A defines the magnitude of F and is given by