Simple harmonic motion is actually a lot like uniform circular motion, mathematically speaking. You can see this for yourself, if you compare the ball's motion on the spring to an object in ...

Simple harmonic motion describes the vibration of atoms, the variability of giant stars, and countless other systems from musical instruments to swaying skyscrapers.

Animation-ish ($60, free demo) is a very simple, intuitive, sensibly progressive tool to learn stop-frame animation based on author and illustrator Peter H. Reynolds’s children’s books.