Free body diagrams close free body diagramA simplified drawing of an object or system showing the forces acting on it. The forces are shown acting away from the centre of a box or dot. are used to ...

**Pre Reqs:** [Intro to Forces](http://scienceblogs.com/dotphysics/2008/09/basics-what-is-a-force.php), [Vectors](http://scienceblogs.com/dotphysics/2008/09/basics ...