The little man on the ladder

Although we might expect that he moves in an accelerating manner, a little manikin is also the one who moves with a steady motion.

The specific way in which it slips down the ladder is possible due to its special design.

The ladder has double rungs and the head of the manikin has grooves at the end of which cylindrical holes are drilled. The grooves 'catch on' the double rungs allowing the manikin descend patiently and keeping it stable on the ladder.

If placed vertically on a rung, the manikin attains a transitory balance. Even a little tilt of its centre of gravity out of the vertical plane makes it turn around the rung; the cylindrical grooves make it possible. Finally, thanks to its potential energy, the manikin descends onto a lower rung and the whole cycle is repeated.