Making the impossible possible!

Many physicists admire the precise manner in which toast contrives to land butter-side down when knocked off a table. The true connoisseur of domestic dynamics, however, will point to the humble wine-bottle cork as a bringer of even greater delight and fascination. To join the aficionados in their investigations, you will need: a cork. (Not one of those new-fangled plastic faux 'corks'; only a traditional, flat-ended cork will do. None of your fancy flared champagne corks, either.)

The Challenge

Drop the cork onto a table, lab bench, or other hard, flat surface, such that it lands standing upright rather than rolling around on its side.

Go on, try it. Not so easy, huh?


What's Going On?

As you will have discovered through empirical observation (i.e. you tried it, and it didn't work), the cork will bounce, tumble, and invariably settle on its side. Attempts to circumvent this behaviour by dropping the cork onto its flat end will only succeed for drops of a few miserable and unimpressive millimetres.

The knack is this: drop the cork on its side, from a height of about one-and-a-half times its own length.

Only very rarely will the cork land absolutely flat-on along its length. We'll call that situation by its technical name - a failure. Much more likely is that one end will strike the table first, so as the cork bounces, it'll start to rotate.

Judge the drop height right, and the amount of rotation will be just enough to bring the cork upright before it strikes the table a second time. The cork will rattle around before coming to settle upright. It's all rather satisfying when it you do it right.

Too high a drop will induce enough rotational momentum to spin the cork through far more than 90 degrees, at which point all bets are off. Too low a drop and you'll feel like an idiot as the cork pretty much just thuds to the table. But the range of heights over which the trick works is rather large (which is interesting in itself), and with a little practice it's possible to succeed about two times out of three.

Try it and see - all those around you will want to have a go when you succeed - just don't tell them how!