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Randall Munroe: Right About Treadmills and Airplanes

Randall Munroe, the mad genius behind XKCD, serves up probably the best analysis of the “Airplane on a Treadmill” debate to date.  Money quote (after comparing interpretations of the problem):

So, people who go with interpretation #3 notice immediately that the plane cannot move and keep trying to condescendingly explain to the #2 crowd that nothing they say changes the basic facts of the problem. The #2 crowd is busy explaining to the #3 crowd that planes aren’t driven by their wheels. Of course, this being the internet, there’s also a #4 crowd loudly arguing that even if the plane was able to move, it couldn’t have been what hit the Pentagon.

Well worth a read.  He also links to some of the finest math/science paradoxes around, so be prepared for a heavy mental workout.

For the record: I’m firmly in the “plane takes off as normal” camp regardless of which interpretation of the problem one accepts.  Any physically plausible construction of the problem can be resolved by the fact that the plane’s engines push against the air and its wheels are merely to provide rolling friction against the ground, instead of having to just scrape the belly of the plane across the tarmac.  This  is the same reason why a plane could take off from a frictionless surface (with or without the landing gear down.)

Posted in Geekery.


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  1. Jack linked to this post on 2008.11.19

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