The following video clips show a mass attached to a spring. The spring is extended by a small amount and then released.
For other examples of periodic motion click here.
We encourage you to set up a spring and a mass for yourself and observe the oscillations.
Suppose you needed to describe the motion of the mass to someone who had never studied the physics of vibrations (say one of your students). How would you do it? What actions would be useful to define? Attempt an answer in the box below: