What’s a Free Body Diagram? A Free Body Diagram portrays the forces acting on a system. To draw a Free Body Diagram you break your system down into a set of simple machines and use the laws of mechanics to analyze how the various parts of those machines balance each other. Drawing one lets you know how the variables in your system relate to each other: how the weight of one object might affect the necessary torque in a motor, or how the angle of a support might affect the kind type of fastener you use, etc.
To start off with, here’s a drawing of my camera on my tripod.