WAVES & SHM SHM a = −ω^{2}x Energy KE=PE at A/√2 Systems Spring | Pendulum Standing Nodes | Pipes Wave Speed v = $\sqrt{T/μ}$ Beats f = |$f_{1}$ − $f_{2}$| Doppler f' = f$\frac{v±vO}{(v∓vS)}$