ABSTRACT
Spinning toys are among the most ancient toys, and there is a great variety of them. It is quite simple to start spinning objects like a top or a gyroscope, and though it is simple to explain their motion in general, it is challenging to write down the detailed equations of motion.Among spinning objects, the tippe top exhibits one of the most bizarre and counterintuitive behaviour. This top, similar to a mushroom (see Figure 1), flips over on its stem after spinning for a while. Although a detailedexplanation of the flip-over is not simple, we note that rotation is only stable around the symmetry axis. It is the friction with the bottom surface and the position of the centre of mass below the centre of curvature which causes the top to rise. Remarkably, at the inverted state, the center of mass lies higher than at the initial condition, defying gravity. Experimentally, it is known that such a transition occurs only if the initial spin exceeds a certain critical threshold.
