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I'm going to post the old, "Airplane on a Conveyor Belt" question. This, of all questions I have seen posted on the internet has caused the most heated of debates.

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I posted this in General because, while it doesn't have anything to do with College Football, most people don't check the Open Forum. If the mods don't want it here, that's cool too. And since ND's class is mostly wrapped up and we don't have anything else to talk about. here it is:

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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?

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My personal opinion, and I am no physicists, but I say the plane doesn't take off b/c while the planes tires aren't meant for propollsion, they are the means to move the plane on the ground. Since the relative motion of the plane is directly counteracted by the conveyer belt's motion, the plane doesn't move relative to the "air", therefor no lift is created.

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People on both sides of the fence seem positive that their opinion is the right one. I believe the show "Mythbusters" is going to be doing this in an upcoming episode, so you would think that that would settle it.

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Anyway, your opinions??????????????????

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Also, no wacky answers like, well, they didn't tell you there was actually a rocket attached to the plane so that makes it take off. Stick to the question and don't add hypotheticals.

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I'm not an engineer, but if the plane isn't moving according to the statement, then there could be no lift from wind. It would be like being on ice and spinning your wheels, you don't move without friction. My vote is no.

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I'm not an engineer, but if the plane isn't moving according to the statement, then there could be no lift from wind. It would be like being on ice and spinning your wheels, you don't move without friction. My vote is no.

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I'm with you but there are some very opinionated ppl who think it does take off...

Not a chance. Lift counteracts gravity and lift comes from air over the wings. All those who say the plane would take off should google Bernoulli.

Not a chance. Lift counteracts gravity and lift comes from air over the wings. All those who say the plane would take off should google Bernoulli.

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Correct. I took an aerospace engineering class in college and Panther is right on. There must be air moving over the wings to produce the lift.

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Anyone on the other side of the fence?

Anyone on the other side of the fence?
i take offense to that remark....... :wink: :wink:
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Anyone on the other side of the fence?
i take offense to that remark....... :wink: :wink:

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You can only take offense if you actually ARE on the other side, the question is, are you? :lol: Or, does your gate swing both ways?

i refuse to answer that question on the grounds that it may incriminate me. BTW, i don't think my gate is big enough to swing both ways... :shock: :p :p

I hate to break the news to you guys, I'm an engineer too and the plane takes-off. What tricks people about this question is the wheels. Planes take off with thrust, they are not "driven" off the runway like a car would be, and because the wheels on a plane are free-rolling and provide very little resistance (force in the opposite direction of thrust) on a moving converyor. Sine the thrust if an airplance is greater than the resistance of the wheels going in the opposite direction - the place takes off.

I hate to break the news to you guys, I'm an engineer too and the plane takes-off. What tricks people about this question is the wheels. Planes take off with thrust, they are not "driven" off the runway like a car would be, and because the wheels on a plane are free-rolling and provide very little resistance (force in the opposite direction of thrust) on a moving converyor. Sine the thrust if an airplance is greater than the resistance of the wheels going in the opposite direction - the place takes off.

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I admit I'm not an engineer but I've had my share of science classes as I' studying for my PhD in chemistry. The issue of thrust would be liek saying there were rockets on the plane. Thrust does NOT make the plane fly. Thrust make the plane move forward and the forward movement causes air to flow past the wings. Due to the shape of the wing, the air moves faster over the top than it does underneath due to it having to travel a longer distance. This means that it will exist at a lower pressure relative to the air moving underneath the wing. This causes lift...and it's lift that makes the plane fly...you need to over come the force of gravity here to make a plane airborne.

I hate to break the news to you guys, I'm an engineer too and the plane takes-off. What tricks people about this question is the wheels. Planes take off with thrust, they are not "driven" off the runway like a car would be, and because the wheels on a plane are free-rolling and provide very little resistance (force in the opposite direction of thrust) on a moving converyor. Sine the thrust if an airplance is greater than the resistance of the wheels going in the opposite direction - the place takes off.

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I admit I'm not an engineer but I've had my share of science classes as I' studying for my PhD in chemistry. The issue of thrust would be liek saying there were rockets on the plane. Thrust does NOT make the plane fly. Thrust make the plane move forward and the forward movement causes air to flow past the wings. Due to the shape of the wing, the air moves faster over the top than it does underneath due to it having to travel a longer distance. This means that it will exist at a lower pressure relative to the air moving underneath the wing. This causes lift...and it's lift that makes the plane fly...you need to over come the force of gravity here to make a plane airborne.

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But you have to remember that the conveyor belt is moving the wheels of the plane, not the thrust of the engines.

Ooooh! :idea: :idea: :idea: I think I'm starting to see another possibility here...because the wheels are not driving the plane as the wheels on a car would make it move.

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I'm going to have to think about it to convince myself, but you've got me thinking. Cool problem!

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(Yes, you may call me sick for enjoying this!)

Ooooh! :idea: :idea: :idea: I think I'm starting to see another possibility here...because the wheels are not driving the plane as the wheels on a car would make it move.

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I'm going to have to think about it to convince myself, but you've got me thinking. Cool problem!

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(Yes, you may call me sick for enjoying this!)

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Bingo...I probably didn't explain it well enough.

would you freaks like to join us on the game day thread?? there is a football game tonite............. :D :D :wink:

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Finally, someone who thinks the other way. I'm still convinced that it doesn't take off b/c i don't think there is anything to create lift. I still think the plane is stationery relative to the "air" around it, therefor no lift.

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It's not like if you are running on a treadmill that you have a headwind.

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