Brainteaser Options

[james]

Here's a question for you:

"A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

A couple of links discussing it (and some funny rationalizations for peoples incorrect assumptions):
www.kottke.org/06/02/plane-conveyor-belt
www.straightdope.com/columns/060203.html

[james]

Yes it will

Think of it like this - how about the conveyer is ramped up to 1000mph (trying to move the plane backwards) - depending on how good the bearings on the wheels are they will spin like crazy and the plane will move backwards a small amount through the friction on the axles (versus the inertia of the fucking heavy plane). When you turn the engines on they push air out the of the back of themselves, causing forward motion, when the forwards motion (speed) of the plane is high enough the aerodynamic properties of the wings will give the whole caboodle lift and it will take off.
As long as the wheels are allowed to freewheel, their effect is almost irrelevant.