Balanced and Unbalanced

http://www.physicsclassroom.com/class/vectors/Lesson-3/Equilibrium-and-Statics

The link above takes you to an image that shows a balanced free body diagram. They're balanced because when subtracted, you get a net force of 0. There aren't any specific forces being shown.


http://www.bbc.co.uk/staticarchive/20fad0f32ad650e6ffc739df241b0824f264f915.gif

The link above takes you to an example of an unbalanced free body diagram. They're unbalanced because on side, you have 8 total newtons and on the opposite side you have only 3 newtons. If you subtract the 8 from 3, you get 5. Since you didn't get a net force of 0, it is unbalanced. Again, there aren't any specific forces being shown.