.....as a simplified "image" , at :
www.youtube.com/watch?v=hesfXBcgV0s (http://www.youtube.com/watch?v=hesfXBcgV0s)
It's a continuous unbalance game of three masses ("heavy points") , due to gravity dynamics and...electricity dynamics ( source of motion ).
"Our game" can be simplified even more : two masses ("heavy points") , playing continuous motion (rotation) , due to gravity dynamics (including the source of motion ) , only.
Al_ex