**Pre-reqs:** None. I intend to talk about forces and force diagrams, but there is a more fundamental question to address first. What is a force? Most texts define it as a push or a pull. That really ...

**Pre reqs:** [Free Body Diagrams](http://scienceblogs.com/dotphysics/2008/09/basics-free-body-diagrams.php), [Force](http://scienceblogs.com/dotphysics/2008/09 ...

Physics, especially the part about forces and motion, often feels like a maze of confusing concepts and formulas. If you’ve ever stared at a problem about an object moving or a force acting and ...

This acts when an object is at rest and prevents it from starting to move. It increases up to a certain limit as you apply an external force to initiate motion. This acts when an object is already in ...