Chapter 4 for Dynamics, Noise and Vibration module (code UFMEAW-20-3) at UWE Bristol.Chapter 4 is entitled Forced Oscillation: Periodic Functions. This chapter talks about how Fourier series can be used to represent non-sinusoidal periodic functions and how to solve vibration problems where the forcing function is a non-sinusoid periodic function. This video includes another example (see previous videos for first example) of applying the theory to a vibration problem. This involves finding the fourier series for a function, then applying it to a mass-spring system. The forcing function is Question 4 in the notes.