Originally posted by: letdown427
"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?"
waaait a minute. a plane is not a car right? Right. A plane is not moved forward by it's wheels right? Right. For the plane to move forwards, air is sucked into the engines (i'm not thinking of a propeller driven plane here, but like, a commerical airliner, irrelevant though) Neway, for it to move forward, this must happen, it mustbe sucking the air into the engine, generating thrust n stuff, fine i don't know for sure the exact technical details, but i actually think it can take off. The plane actually moves forward independent of the ground. its wheels stop it from dragging on the floor nothing more. so if the plane is moving forward at say 140mph (to take off) yes, the conveyer is moving at 140 opposite direction, but this just means that the wheels are moving at 280mph. the planes speed is created in the air if u will, by the engines, not by the wheels. therefore, i think it can take off. contrary to my initial assumption of this is a duuuuumb post. do i win? lol
like, imagine a strong fan, on wheels, blowing air backwards on one of these conveyers. say it blows air out at a rate sufficient to get it to move forward at 10mph. now, assuming there is no resistance as we always do in simple physics, it will move forward at 10mph whether it is in thea air, on the ground on its wheels, or even in the sea (sticking to NO RESISTANCE here). if it was on this conveyer, all that would happen is that it would still be moved forward by the fan at 10mph, but the wheels would be traveeling at 20mph, ass they conveyer would be moving opposite to the wheels under it.