questionsdoes the plane fly?

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Ground rules: You have to briefly explain your reasoning.

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No, because there is no wind force under the wings to provide lift off.

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Who is pushing the treadmill?

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they did this one on mythbusters with a giant "treadmill" and an airplane.
it's not the speed of the wheels rolling that creates lift, it's airflow over the wings.

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@faughtey: Whichever minion it was that built that "killer" app yesterday...

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@skippykj: There's no wind? There should be wind... did someone put my experiement in a vacuum bell when I wasn't looking? looks around

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@dosquatch: Building off what @kamikazeken said, liftoff requires a minimum of airflow stronger than could naturally occur. I'm assuming that the plane can only remain stationary relative to the Earth because the treadmill will counter any force from the plane's engines. If a plane can't move forward creating that airflow, it needs to come from another source at hundreds of miles per hour.

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@skippykj: Correct, airfoils require movement through the air to generate lift. I could split hairs about "naturally occurring" and point out how many small planes get tossed around by hurricanes and tornados, but that's outside of the scope of this particular puzzle.

Who said stationary relative to the ground? The second sentence says "the plane moves."

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This is older than the internet.

Here's the real dope:

The bearing in the planes wheels will overheat and crack, rendering the wheels stuck before the plane makes enough speed, since the wheels are spinning twice as fast as they were designed to. Then the plane, stopping short, tumbles over and overturns a cabbage cart.

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@vinithehat: That's a dodge. Let's assume the bearings will survive being pushed past design specs long enough to see the puzzle through.

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@dosquatch: if the wheel are frictionless, the treadmill is rendered ineffective; the plane flies. There's no conundrum.

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The reason the Mythbusters experiment worked the way it did (i.e., the plane took off) was because the treadmill actually exerts little to no force on the plane. This is because the wheels of the plane spin freely, so when the treadmill surface moves, it only interacts with the freely spinning wheels. Inertia keeps the plane in generally the same position relative to the ground. The propeller generates significant forward movement of the plane relative to the ground which, unimpeded by the speeding treadmill surface, causes air to rush past the wings, generating lift.

Here's the video of the Mythbusters' experiment end:
http://www.youtube.com/watch?v=YORCk1BN7QY

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So theres a sea-plane, flowing backwards down a river...

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@vinithehat: I didn't say frictionless, I said "survive". You'd be surprised how long a wheel will keep rolling on a trashed bearing.

Bearings are meant to reduce friction anyway, relying on a friction-reducing device to provide brakeing power doesn't seem wise.

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@sirlouie: Correct as to the mechanics, good job.

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@dosquatch: Well. it flies.

Although I hate the mythbusters, I'm glad they closed this case. If they could only endeavor to cancel Dr. Who, the internet would be much more efficient.

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@vinithehat: ...and the river is flowing northward.