This document discusses modeling mechanical systems for control systems. It covers: 1) Newton's second law governs mechanical systems and results in equations of motion describing dynamical systems. These equations can be represented using block diagrams and Laplace transforms. 2) Modeling involves determining the equation of motion using free body diagrams and summing the forces. Mechanical components like springs, dampers and masses have characteristic force-velocity, force-displacement and impedance relationships. 3) Systems with multiple degrees of freedom require equations of motion equal to the number of independent motions. Transfer functions can be derived from the Laplace transform of the equations of motion.