[EricH]

Originally Posted by Don Rotolo

Here we go again.
The key to this puzzle is the statement in the initial conditions "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)."
As soon as the thrust of the engine pushes the plane forward some small distance (thus it has some speed), the conveyer moves at whatever speed necessary to counteract that speed. It can move at any speed!

Ummm... Don, I don't see how you can say that the belt can move at any speed.
The condition says that the speed of the conveyor is (effectively) the negative of the speed of the airplane. It does not say that the conveyor goes fast enough to stop the plane with friction. It does not say that the conveyor is attached to the wings or tail (which would be necessary to stop the plane from taking off unless the brakes were on).

All it says is that the conveyor moves at the same speed as the plane in the opposite direction.

That said, guess who's going to be watching Mythbusters next Wednesday if at all possible?