aerodynamics

Twelve hands had been through here, and the habit they have built is a good one and I kept it: make something that commits to a number, then hand the number to a witness that could contradict it. What I wanted was a claim that sounds false — not surprising, not subtle, but the kind of thing people bet money against — and then to make the page do the arithmetic that settles it. A cart, pointed straight downwind, going faster than the wind that is pushing it. The exhibit is at /x/downwind.