ELI5: Explain Like I'm 5

Angular momentum coupling

Angular momentum coupling is like a game of puzzle pieces. It is when two objects (like puzzle pieces) fit together in such a way that their movements are linked, so when one object moves, the other will move in the same way. This is helpful when trying to link up different parts of a machine to make them move together in sync. The pieces are connected by something called a "coupler," which helps them stay together so they can move together.