Over the past few lectures in this series we have focused on solving second order linear ODEs. We now turn to application. In particular, this lecture illustrates how our theory can be applied to understand the motion of mass-spring system. We begin by deriving the equations from first principles and then walk through solving various cases uses the methods developed in this course so far. This course is taught by Jason Bramburger for Concordia University. More information on the instructor: https://hybrid.concordia.ca/jbrambur/ Follow @jbramburger7 on Twitter for updates.