System of Forces:

You shall recall Newton's First Law of Motion which helps us to describe a force as an external agency that tends to change the state of rest or of uniform motion of a body.

Force tends to generate motion in a body, alter the motion of a body or checks the motion of a body. In simple terms, the action of one body on any other body may be called a force. These actions can be of several forms: pull or push on a body, gravitational force called as weight of a body, force exerted through an elastic spring, force exerted through a locomotive on the train, resistance offered through the track, etc.

To identify a force, you have to know its magnitude, direction & the point of application. The magnitude is expressed as Newton in SI unit. Graphically, a force is represented by drawing a line to scale, indicating its magnitude, and after that arrowhead indicating direction. Such a straight line is called as a vector.

A combination of various forces acting on a boy is called as system of forces or a force system.