Introduction: basic concepts and definitions in mechanics.

This introduction aims to expound the basic ideas of mechanics of materials to clinicians. What happens when a bone (mechanically a beam) is submitted to standard loads: Centric axial load, bending, eccentric axial load, torque? How does the bone deform? The basic ideas of mechanical engineering are presented using an eraser under load as an illustrative object, and trying to maintain the mathematical formulae as far as possible.