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#391
11-23-2005, 06:22 PM
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Re: think about this...
[ QUOTE ]
[ QUOTE ] [ QUOTE ] There is a plane (Boeing 777, prop plane, whatever) on a moving, conveyor-type runway. The runway moves in the opposite direction of the plane at the exact same speed as the plane's wheels. There is no wind. Can the plane take off? [/ QUOTE ] Yes. [/ QUOTE ] BIMO [/ QUOTE ] Kay, I'm gonna look stupid now, but remind me what bimo means again? 
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#392
11-23-2005, 06:23 PM
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Re: think about this...
[ QUOTE ]
[ QUOTE ] Patrick, you actually enjoy watching this thing spiral out of control, don't you? I expect to see pwnage the likes of which OOT has never seen. I am looking forward to this more than I am Dominic's next porn bloopers post (well almost [img]/images/graemlins/grin.gif[/img]). [/ QUOTE ] It is pretty entertaining. This is the kind of [censored] that OOT is supposed to be about. Don't get too excited - I really don't see what's so complicated about this problem, so my explanation will be pretty simple. [/ QUOTE ] I'm hoping you can do it in 30 words or less. The shorter and simpler, the more devasting it is to the non-believers.
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#393
11-23-2005, 06:31 PM
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Re: think about this...
[ QUOTE ]
[ QUOTE ] [ QUOTE ] Patrick, you actually enjoy watching this thing spiral out of control, don't you? I expect to see pwnage the likes of which OOT has never seen. I am looking forward to this more than I am Dominic's next porn bloopers post (well almost [img]/images/graemlins/grin.gif[/img]). [/ QUOTE ] It is pretty entertaining. This is the kind of [censored] that OOT is supposed to be about. Don't get too excited - I really don't see what's so complicated about this problem, so my explanation will be pretty simple. [/ QUOTE ] I'm hoping you can do it in 30 words or less. The shorter and simpler, the more devasting it is to the non-believers. [/ QUOTE ] Well, in that case: F=ma. The conveyor imparts no force on the plane to counter thrust because the wheel bearings are frictionless. In the absence of this counter force, the plane will accelerate forward.
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#394
11-23-2005, 06:32 PM
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Re: think about this...
[ QUOTE ]
[ QUOTE ] I finally got hooded to admit defeat. The easist way for us to think about it was the rollerskate on treadmill example. If you are pulling yourself forward on the treadmill, you are going to go forward no matter what your [censored] wheels do. you are going to move forward! the hang up is that the OP suggests that the plane somehow is not able to accellerate forward but the fact is that it WILL accellerate forward. THe only thing stopping it is the wording of the problem which suggests its going to stay in place, but taht is not what is going to happen. edit-actually, it doesnt even say anything about that in the OP. that must have been concluded by people later in the thread. [/ QUOTE ] Good. Anyone who can't understand after thinking about the rollerskates on treadmill example or the stroller on moving walkway example is just a fool. Anyone trying to get out of this with some BS about they thought the OP said the wheel's CG is moving at the same speed as the conveyor is just an idiot trying to back out of being wrong. [/ QUOTE ] Wait a sec, though Patrick. The faster a treadmill is going, the harder I have to pull to move forward on it. If the treadmill always moves faster to keep up with how hard I'm pulling, why is it so obvious that I go forward when I pull forward on the treadmill handle? Forget the skates for a second. If I'm dragging on a treadmill and pull myself forward, if the treadmill keeps going faster, at some point I will get pulled off of it. I am assuming some friction between my shoes and the treadmill. My initial reaction was that we could obviously take off, for what I believe are similar reasons to yours. However, now I am beginning to think that this mythical conveyer belt counteracts the force. OK, back to the treadmill question. We have wheels and a treadmill. Now I pull forward and I move forward. Good enough. But if the treadmill speeds up now, is this different than someone pulling me backwards? Is the treadmill speeding up different than someone pulling me back to counter my pulling forward? Hmmmm.... Is wheels spinning different than feet dragging? Now are we just into a whole frictionless or not deal? Edited to add: ok, ignore most of this. NLSoldier just told me we are talking frictionless bearings.
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#395
11-23-2005, 06:33 PM
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Re: think about this...
Obviously the plane moves if you ignore the "runway moves in the opposite direction of the plane at the exact same speed as the plane's wheels" stipulation. The fact that we took the original post at face value rather than ignored this impossible stipulation doesn't make us "idiots".
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#396
11-23-2005, 06:34 PM
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Re: think about this...
[ QUOTE ]
But if the treadmill speeds up now, is this different than someone pulling me backwards? Is the treadmill speeding up different than someone pulling me back to counter my pulling forward? [/ QUOTE ] Im pretty sure this question is the key. And im pretty sure the answer is that it is indeed different. the speeding up of the treadmill is going to affect the wheels only. Its not going to affect how hard we have to pull to move forward. edit-yeah patrick says it better than me: [ QUOTE ] F=ma. The conveyor imparts no force on the plane to counter thrust because the wheel bearings are frictionless. In the absence of this counter force, the plane will accelerate forward. [/ QUOTE ]
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#399
11-23-2005, 06:44 PM
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Re: think about this...
[ QUOTE ]
[ QUOTE ] [ QUOTE ] [ QUOTE ] Patrick, you actually enjoy watching this thing spiral out of control, don't you? I expect to see pwnage the likes of which OOT has never seen. I am looking forward to this more than I am Dominic's next porn bloopers post (well almost [img]/images/graemlins/grin.gif[/img]). [/ QUOTE ] It is pretty entertaining. This is the kind of [censored] that OOT is supposed to be about. Don't get too excited - I really don't see what's so complicated about this problem, so my explanation will be pretty simple. [/ QUOTE ] I'm hoping you can do it in 30 words or less. The shorter and simpler, the more devasting it is to the non-believers. [/ QUOTE ] Well, in that case: F=ma. The conveyor imparts no force on the plane to counter thrust because the wheel bearings are frictionless. In the absence of this counter force, the plane will accelerate forward. [/ QUOTE ] This is all true and isn't what we (or at least I) am arguing. What we want you to explain is how can a wheel move with respect to the runway if they are going the same speed.
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#400
11-23-2005, 06:53 PM
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Re: think about this...
[ QUOTE ]
You are exactly where I am at with this problem. The only way I can see it being reconciled is to assume that the conveyor belt will accelerate up to infinity along with the wheels. Then the plane moves forward with its wheels spinning at infinty + some speed sufficient for takeoff, which still equals infinty. [/ QUOTE ] Exactly. I mentioned this at least a page ago. Infinity +1 > infinity. So the conditions of the OP are still not met. Patrick is of course right that it doesn't matter which way or how fast the wheels are rolling as they have nothing to do with the thrust of the engines. However wheel speed is not going to equal conveyor speed. It just ain't. That's why the situation is impossible. I think 98% of us realize that the plane can take off. It's not that the plane can't take off because speed(wheels) = speed(runway). It's that the plane will take off but speed(wheels) will be > speed(runway).
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