9 pages on topic, impressive. Unless the runway is moving air, you've got nothing but a over-powered paper weight.

I changed my mind. Bruce is right; the jet engines aren't pulling air over and under the wings; in fact, the engine doesn't even have to be on the wing. The engines are pushing the plane to achieve atmospheric air flow over and under the wings. Since the treadmill plane isn't moving relative to the atmosphere, the needed air flow around the wings doesn't happen and there's no lift; just a lot of engine revving and wheel-spinning. It doesn't matter what 'ground speed' the instruments record, the plane has no velocity relative to the air around it. The thing won't fly, any more than a kite will fly if you hold its string while running on a treadmill.

That's my story, and I'm stickin' to it. :p

and it keeps the covers from falling down into the sewers

*pokes head into room.....realises is totally out of depth and retreats*

But the engines still exert a force against the body of the aircraft, and since the runway can't exert any force in the absence of friction, their is a net acting force on the aircraft

but no lift

Yes, I forgot that important part. :thumb:

Nope, the engines push the plane through the atmosphere (air), and what the ground and wheels are doing under it has absolutely no bearing on the plane moving through the air. Up she goes, into the wild blue yonder. Flying high, into the sky. :cool:

That's just what the engines don't do in the case of the treadmill plane. They aren't moving it through the atmosphere. It's stationary with respect to the air around it, therefore no flow, therefore no lift.

If you run on a treadmill, does air flow past your face (assuming no fan!)?

Oh, Kay....but where in the original post does it say that this hypothetical plane...has wings?

The plane isn't running on a treadmill, that's not how it moves. It moves by pushing through the air...the treadmill has no bearing on the plane. :headshake

Nor combustion w/o supplied oxygen.

Another example of the unimportance of wheels relative to a plane's taking off.
Ski planes and water planes have no wheels, hell, if a plane were lying on its belly on a greased treadmill it would take off.

There are two interpretations for this. Both are possible, but neither is specified by the provided information.

#1: If the "forward speed" is defined as relative to the treadmill then the plane is stationary relative to the air.

#2: If the "forward speed" is defined as relative to the ground, then it is possible for the plane to be in motion relative to the air.

Nothing in the question rules out either of these interpretations, and no amount of blustery hoopla or physics masturbation can change that.

The question is unanswerable as stated. It's designed that way on purpose.

Okay, this is the absolute last post I'm going to make on this subject. (promise!) If the wheel experiences a force, that force must be transmitted to the axle. (The other alternative is that the wheel goes that-a-way while the rest of the plane stays put.) The free body diagram holds.

The straight dope misses this point:
That "pull yourself forward easily" is impossible. To move yourself forward at all (even a micron per hour) still necessitates a net imbalance in the forces acting on the axle of the wheel; this is patently impossible, given the wording of the problem. F1 == F2 by the very statement of the scenario, so no net motion.

Newton would be scratching his head.

I'm with Flint and Pie. I wholeheartedly agree that, IF THE PROBLEM WAS REALISTIC AND SAID WHEEL SPEED, NOT PLANE SPEED, it would definitely take off. But the problem doesnt say that. It's unanswerable, because plane design + physics =/= the actual problem.