Jumps and capers

The smiling puppet descends the plane in a uniform motion. It turns itself upside down cutting capers.

Inside the puppet there's a sphere whose mass has been chosen so that it will remain in the superior part of the puppet in the instant of the overturn. Moreover, the little puppet's hands are collocated in an asymmetric way with respect to its axis, i.e. in a way that if we place the puppet on the stairs vertically, a non equilibrated moment of forces is generated by a couple of forces: the weight applied in the bary-centre and the reaction in the point.

Anyway, to make the puppet discend the stairs, we have to place it with the right inclination angle..