Unicycle

hold to pedal. try to get somewhere.

a five-metre unicycle on a salt flat at noon: hold to push the pedals, let go to push them back; you only go forward by letting yourself fall. A friend's hand on the mast slows your falls for the first eight metres of every ride

On one wheel you are a pendulum standing on its pivot. Holding a lean means speeding up at g x tan(lean), so you can't pedal off from upright: you let yourself tip, then drive the wheel back under you. Stopping starts by speeding up. A friend's hand slows your falls for the first 8 m; the first milestone is five turns of the wheel on your own.

Concepts: balance, gravity, pendulum.

An interactive you play with one thumb, on Wundr.