It takes off

We watched the Myth­busters tackle the “Air­plane on a Con­veyor Belt” issue last night. They did not really build a huge con­veyor belt (they essen­tially used a long can­vas tarp to pull the run­way out from under the plane), and so the result (the air­plane took off) won’t really sat­isfy every­one. But, it remains the right answer.

Here’s some back­ground: the kot­tke post that started it all, the expla­na­tion for the sci­en­tif­i­cally minded (the com­ments are fun), and kottke’s live­blog­ging of the Myth­busters episode.

Here’s how I try to explain it. An air­plane fly­ing through the air is vir­tu­ally no dif­fer­ent than one “fly­ing” on the ground. The one on the ground is not (yet) going as fast as the one in the air, and there’s a minis­cule amount of fric­tion act­ing on the bear­ings in the plane’s wheels, but really, they are mov­ing under the same laws of physics. Air­plane pushes on the air, and moves for­ward. What the ground, or the con­veyor belt are doing to the wheels is largely irrel­e­vant. No mat­ter how fast the con­veyor belt goes, all it is act­ing on are the wheels of the air­plane, not the plane itself. It can make those wheels spin crazy fast, but the plane will still take off.

So there.

Oh, and I like the sen­ti­ment of kottke’s t-shirt, but I’d like a pic­ture of a plane on it, frankly. And a con­veyor belt.