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

[Egg Designer]

For the love of God! Cam - read the first post about the conveyor belt counteracting the forward motion provided by the thrust of the jets, therefore making the groundspeed of the plane effectively zero, we are not debating friction or the jets ability to overcome the effects of the conveyor belt, the jets on a plane only provide thrust, not lift - as we all know - but you need speed across the ground to achieve the lift. If in the case we are looking at we take it that the surrounding air is stationary (hypothetically) A plane needs to have air moving at speed underneath its wings to take of, the above example has a planes forward motion, in theory, at zero, therfor zero lift created.

Basic physics - just the same as beating with a stick! :)

[camsmith]

For the love of God! Cam - read the first post about the conveyor belt counteracting the forward motion provided by the thrust of the jets

Basic physics - just the same as beating with a stick! :)

OK, I haven't replied to this for a little while.

Rory, Rory, Rory... Where do I begin.

The words are NOT that the conveyor belt moves fast enough to counteract the jets... it simply moves in the opposite direction at the same speed as the plane. YOU are the one who is assuming (quite wrongly) that this is enough to counteract the forward motion. It is not. It is simply making the wheels spin twice as fast.

The plane moves through the air, the ground is simply there to hold it up until the wings can take over.

If you like, I could show you where to put the stick