Incidentally, what are the applications of sine waves?
Can't remember that gif, was it something like a spoke or radius rotating in a circle with the resultant wave form?
In both mechanical and electrical theory sine waves are very important, they are the "shape" of the electricity from your sockets, the basic shape of the "carrier signal" in radio transmissions and the shape of any pure audio tone. It is also the wave shape that would be drawn by a weight bouncing up and down on a spring. Remember the old "Spirograph"? That could draw sine waves if you set it up right, even sine waves in a circle to make sort of flower patterns - great fun!
The number of waves per second gives you the frequency, so a 1 kiloHertz tone would be 1000 full waves, or cycles,, like a "S" on its side, per second. Hertz was the guy credited with discovering this cyclic nature when he nannaged to transmit energy, through the air, from a "transmitter" to a "receiver" - Marconi cashed in by sending "intelligence", a Morse code message, using Hertz' principles.
Wikipedia has, of course, an article on them:
https://en.m.wikipedia.org/wiki/Sine_wave. The full name is "sinusoidal waveform"