This document provides an introduction to the analysis of dynamic systems with one degree of freedom. It describes linear systems and how their motion is governed by linear differential equations. It also covers the properties of linear systems including superposition and steady-state response to harmonic excitation. The chapter then discusses modeling an elementary dynamic system using mass, spring, and damping properties. It derives the equations of motion and solves for free and damped vibrations, analyzing the effects of damping. Stability criteria for systems are also introduced.