Chapter 2 — Oscillators
From simple harmonic motion to driven resonance.
Before we have a wave we have a vibration; before we have a vibration we have an oscillator. The chapter walks the canonical sequence — free SHM, damping, driving, resonance — partly as a refresher and partly because every concept here returns when oscillators are coupled into a continuum in the next chapter, and again when we Fourier-decompose a wave field into independent oscillating modes in chapter 8.