Editing Harmonic oscillator (section)

====Energy variation in the spring–damping system====
In terms of energy, all systems have two types of energy: [[potential energy]] and [[kinetic energy]]. When a spring is stretched or compressed, it stores elastic potential energy, which is then transferred into kinetic energy. The potential energy within a spring is determined by the equation <math display="inline"> U = \frac{1}{2}kx^2. </math>

When the spring is stretched or compressed, kinetic energy of the mass gets converted into potential energy of the spring. By [[conservation of energy]], assuming the datum is defined at the equilibrium position, when the spring reaches its maximal potential energy, the kinetic energy of the mass is zero. When the spring is released, it tries to return to equilibrium, and all its potential energy converts to kinetic energy of the mass.