Re: Physics graduate from Daryn\'s alma mater\'s answer
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The thing is, as stated in the original problem, the runway speeds up to compensate for the extra +x force.
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But that's the issue here, CAN the runway compensate for the thrust of the engines? Imagine the wheels are frictionless, and the conveyor belt is spinning backwards at 100 mph and the plane is just sitting there, engines at idle. The conveyor belt has no effect on the plane and therefore has no way to counteract the thrust of the plane.
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Yes but in that situation, for the air speed to be > 0, the speed of the wheels has to be > 100. The plane will take off, but the wheels and conveyor will not be going the same speed, therefor the conditions of the OP will not have been met. I'm still waiting for someone to explain where I'm wrong.
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You've mentioned this five times now, and you've been right each time, but they're just not understanding what you're saying of course. The plane can take off, for all the reasons stated already, but when it does take off, the wheels will be moving x mph faster than the conveyer belt, where x=the plane's velocity relative to the ground/air/whatever.
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