Animals at large

The animals descend an inclined plane, but they don't move in an accelerated motion. They go down by awkward steps, swinging forward and back.

During the motion the position of their barycentre changes. They have only two legs and each one ends in a rounded foot. They don't slide thanks to friction between the paws and the plane.

Ducks and Hare are almost anti-educative: motion on the inclined plane, but uniform.