# The Cubli; Laws of Motion and Angular Momentum at Play

Submitted by Charlton Stanley, Guest Blogger

Ever since I was a kid, wheels, gears and spinning things held a fascination. I suspect that is true of most youngsters. One of my all time favorite Christmas toys was a gyroscope. When I took physics, my favorite subject was Mechanics, especially when I got to play with the lab equipment that demonstrated angular momentum and Newton’s laws of motion. I did a bit of  research on the history of the discovery of the laws of angular momentum and inertia. Seems Descartes first formulated it, then Newton used Descartes’ ideas in developing his Laws of Motion. When adding the discoveries of Newton and Descartes together, we get the Law of Conservation of Momentum. Several years after Newton published his Laws of Motion, Euler first wrote the formula F=ma.

The physical laws governing Mechanics, like all other branches of scientific discovery, were discovered piecemeal. The process of discovery took place over centuries. There were many investigators, some more prominent than others. The thing I find interesting is the fact that the significance of the piecemeal discoveries were not always understood at the time. That is particularly true of momentum, which was discovered almost like the palaeontologist scratching dirt away from a fossil, a bit at at time. However, Sir Isaac Newton is given credit for creating the branch of physical science we call Mechanics.

All those discoveries makes the Cubli possible, but we had to wait for computers to be invented to make it work. What, may you ask, is a Cubli? Good question. The name “Cubli” is derived from the English word “cube” and the Swiss German diminutive “li.”  The Cubli is a cube 15cm on each side. It contains three reaction wheels that act as the force generators. Their spin is controlled precisely by the computer. It is a mistake to think the Cubli works by gyroscopic force. It doesn’t. The wheels are spun, then suddenly stopped. That creates the reaction force needed to make the Cubli do what it does.

Take a look over the jump to see the Cubli in action.