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About LinkBacksbut.. does chicken take off??
but.. does chicken take off??
VodkaOriginally Posted by Ephesians
Only to cross the road.
Interesting response...
But that is exactly the opposite to what I was saying. Whether you're on a road, treadmill or whatever, the outside of the wheel has a speed regardless of the motion of the rest of the object, so you can get it above 0mph without moving forwards if your road is moving against you.
My main point was that a wheel can have two speeds, a forward-motion and a spinning motion, these two speeds can be very different to each other at the same time. Saying that the treadmill matches the speed of the wheel without specifying which speed, you would assume they were the same types of speed, leading to two possible conclusions:
1) The speed is the direct movement in relation to the scene, forwards, backwards, whatever. In the case of the wheel this will match the speed of the plane, and everything's fine, in the case of the treadmill if it matches this type of speed then the whole treadmill will move.
2) The speed is related to the outer surfaces of the spinning objects. In the case of the wheel this is the amount of rubber/ground contact in a specified amount of time, in the case of the treadmill this is the surface of the rotating conveyor-belt. (The infinite speed case)
What you have come around to saying however is that the wheel motion is measured as in case 1 and the treadmill as in case 2, mixing the terms of "speed". Without this bit of information it is impossible to say that anyone has the "correct" answer.
1.21 GIGAWATTS!!!!!
Have to agree with chicken on this point. When I first read the conundrum, I assumed it meant the rotational speed of the wheels, not the linear speed. If it meant the linear speed, then it could have been phrased "...match the speed of the plane, but in the opposite direction...", making the whole problem clearer. With the rotational speed, you have this whole positive feedback problem and inifinitive speeds.
Assuming linear speed, then realistically the wheels should be able to cope going twice the usual speed when taking off. Most of heat and forces generated in the wheels would come from landing and braking. Also, as already mentioned, aircraft components tend to have a safety factor of at least two anyway (for a brief amount of time).
It does not make any difference if t means the wheels rotational speed or the linear speed of the plane.
This thread is a bloody treadmill
Does it matter whether we are talking about linear or rotational speed of the wheels? Assuming that the wheels are frictionless, they could spin at whatever the hell speed they like. As long as we have thrust from the engines (which wouldn't be transmitted through the wheels) to propel the plane forward, this poor plane will take off at some point. (apologies if I've missed something here, I decided to skip the last 17 pages)
You are quite right FatalSaviour.
This thread is getting very worrying now.. maybe the mods could just sticky the answer..
Well I'd like to but there's about a gazillion people that don't get it and will forever continue to argue this point rather than just read the thread...
Tbh, I'm thinking of banning JP if he EVER produces a thread like this again!
Only in as much as it's the opposite side of the wheel. You could have alternately said "Hhhhmmm when I am driving at 120mph, the top of my wheels are travelling at 240mph, so I'm off down the road to buy some part-worns from the Ferrrari Formula 1 team."Interesting response...
But that is exactly the opposite to what I was saying.....
If that's your 'main point' it's a bit spurious; because that is not a definition of speed that is in common usage at all. And if you start out with that definition you cannot construct the treadmill (it becomes logically inconsistent, it cannot be defined to behave as such), so you can't really begin to think about answering the question. Or at least, you can and the plane still takes off but you have to put with infinite speeds to get there.
Strictly speaking, your answer boils down to "No the plane doesn't take off, because I insist on continuing to deliberately mis-read the question and because I am doing this I cannot construct a hypothetical treadmill that behaves in the way that everyone else's does, so no treadmill exists, so the plane can't take off".
Don't think I could if I tried...
Tbh, I'm thinking of banning JP if he EVER produces a thread like this again!
The only other one I know is:
A weightless frictionless pulley hangs from a fixed point, through it is threaded a weightless inextensible rope on one side of which clings a monkey of constant weight and on the side at exactly the same distance from the pulley is a weight exactly equal to the weight of the monkey. The monkey starts to climb up the rope. Does the weight move up, down, or stay where it is?
I don't think it'll catch on though. I think most people would shrug and if told the answer, just take it at face value (I know I did). But put a plane on a treadmill and everyone thinks they're Stephen Hawking...
Weight stays still?
The monkey and the weight will always stay opposite one another (exactly the same distance from the pulley), whether the monkey climbs up or down. So if he climbs up, the weight moves up too. That's what I was told anyway, but it seems to make sense.
Yeah, that does make sense - the system has to be in equilibrium after all.
Up cos the rope is moving down on the monkey's side.
Wow, I was going to leave this but you continue to completely misread my posts then accuse me of doing so! What the heck are you going on about the top of my wheels travelling at a different speed? What I meant is the entire wheel, whether spinning or not can move at a speed, in a line, forwards, regardless of what speed it is rotating at. They are two entirely different forms of motion and you can't go combining them willy-nilly without telling people that in the explaination!Only in as much as it's the opposite side of the wheel. You could have alternately said "Hhhhmmm when I am driving at 120mph, the top of my wheels are travelling at 240mph, so I'm off down the road to buy some part-worns from the Ferrrari Formula 1 team."
If that's your 'main point' it's a bit spurious; because that is not a definition of speed that is in common usage at all. And if you start out with that definition you cannot construct the treadmill (it becomes logically inconsistent, it cannot be defined to behave as such), so you can't really begin to think about answering the question. Or at least, you can and the plane still takes off but you have to put with infinite speeds to get there.
Strictly speaking, your answer boils down to "No the plane doesn't take off, because I insist on continuing to deliberately mis-read the question and because I am doing this I cannot construct a hypothetical treadmill that behaves in the way that everyone else's does, so no treadmill exists, so the plane can't take off".
Anyway I'm going to leave this as I believe the initial question is flawed and missing vital information, making the whole 20-odd pages of this pointless.
1.21 GIGAWATTS!!!!!
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