Jumps and capers

This toy shows us how gravitational potential energy gets converted into kinetic energy and into work against the friction forces. The motion is quasi-steady one, as it was in the case with the duck and elephant.

The secret of its design lies in a proper choice of the size of the puppet and the weight of the sphere so that at the instant of overturn the sphere would remain inside the upper part of the puppet. In addition the 'arms' of the puppet are asymmetric to its axis so that when we place the puppet vertically on the stairs, a non equilibrated moment of forces is generated by a couple of forces: the weight of the puppet and the reaction force at the fulcrum.

Yet, another essential construction aspect of the toy is a proper choice of the angle at which the stairs are sloping. By lowering the slope we can find the angle at which the puppet will not descend any more. That means that the increase of the kinetic energy in one pace is insufficient to compensate for the work against friction forces.