think about this...

[NLSoldier]

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I'm going to agree with goofball. According to the phrasing of the OP, the plane is not moving. It's not that the plane is stationary because the plane is like a car and thrust by its wheels, nor because it's physically impossible for the plane to move relative to the ground/air when on a conveyor belt, but rather, the plane is stationary because that's how the problem has been defined. If the plane moves forward any amount relative to the ground such that lifting off would become possible, the criteria laid out in the OP (wheels movement = conveyor movement) is no longer met.

This is not about aerospace engineering, rather so much as it is about reading comprehension (or more precisely, poor phrasing in the original post).

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I second this

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This is exactly correct, and as a side note, I'm sitting right next to NLSoldier, and when he saw this, he said "Don't worry, Pat will come back on and pwn him in a sec!"

Somone tell that donk he owes me 400$....I mean seriously, he just said "I wasn't going to make you pay anyway."

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If you guys can wait (possibly days - my schedule's tight), I'll come up with a full explanation of the whole thing, completely with pictures and everything. Don't get too excited, because it really isn't nearly as complicated as everyone's making it out to be. I really shouldn't even be looking at this right now, but I can't help it - I need to just shut my laptop down.

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Heh, yeah we can wait. No money is gonna change hands anyways because even though hes wrong im not gonna make him pay, and if he wants to insist that he won the bet then thats fine too, ill just cut the $400 off of a huge unpaid debt of his from 10th grade.

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So, if i understand this correctly. The runway is moving backwards at say 300km/h, this would mean the wheels, ie the plane is moving forwards at 300km/h. Isn't it really this simple? or am i missing something.

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Here is what you are missing.

Say that is the case, now the engine turns on, thrusting the plane forward with respect to the atmosphere, generating lift. However, the wheels and runway are now moving at different speeds, thus contradicting the OP.

In essence, you cannot add force from the engine without violating the assumptions of the problem.

ok, now i only owe him $100 from that time i bet him $500 that noone was in the bathroom

[fnord_too]

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yeah it def. blew my mind. now give the answer plz? and the answer to daryns skateboard thing too. me and my friend have a bet on both.

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The plane can take off - this has already been established.



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I thought we determined it was a physically impossible scenario (contradicting assumptions)

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Huh? Noone thinks you can actually build such a contraption, but theoretically it could take off.

What contradicting assumptions are you speaking of?

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There are 200 replies (WTF???) between here and the end, so this may be a repeat, but the asumption that the wheels and track are going the same speed in opposite directions. Since there is no way for the track to apply a force to the plane, the wheels will be going faster than the track, that is, the track can never catch up in speed.

[ddubois]

The only way Pat can own me here is if he uses a different interpretation of "The runway moves in the opposite direction of the plane at the exact same speed as the plane's wheels" than the one I am using. I consider conveyor belt movement to be ft/sec over its pulley, and wheel movement to be ft/sec over its rolling surface.

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sure they are - the conveyor velocity simply accelerates instantaneously with the wheel's tangential velocity.

but as Patrick said, these accelerations have absolutely nothing to do with the forward acceleration of the plane.

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But if there is any tangential velocity of the wheel with respect to the conveyor belt, doesn't that mean that they are operating at different speeds?

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Velocity at what point on the wheel? The only meaningful points in this context are the wheel center and where the wheel contacts the conveyor. The velocity at the wheel center is the same as the plane's velocity. The velocity where the wheel contacts the conveyor is the same as the conveyor and the velocity's magnitude varies linearly between these two points. In the general case, they're not the same.

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Bro, you're claiming a car can travel 1 mile with respect to the ground while its wheels have only covered 3/4 mile.

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No. You are an absolute fool if you believe all the crap you've posted in this thread. Don't worry, though, I'll include this little concept in my fury.

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Patrick, all I want to hear from you is an explanation of how the plane will move forward with respect to an observor GIVEN that the wheel speed is the same as the runway speed with respect to an observor.

This would make my day.

[LAGmaniac]

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I'm sad.

I saw this thread a few hours ago, and thought it would be a 10 reply thread, then die in obscurity. I'm saddened greatly that there can be any sort of debate about this.

It's WINDSPEED that enables lift. If the plane isn't moving relative to the wind, it ain't going up.

As a very correlate aside, planes take off into the wind. They also land into the wind.

So saddened.

Josh

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I thought it was that simple when I first looked at it but it really is not. Nobody in this thread disputes that you need air flowing over the wings (forward movement) to create lift, (thank god).

The issues are whether the forward movement of the plane is prohibited by the conveyor belt, the original conditions of the problem, or neither.

if theye perfect bearings, the plane moves along the runway and takes off normally; if its a normal plane, it doesnt move and hence doesnt take off

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sure they are - the conveyor velocity simply accelerates instantaneously with the wheel's tangential velocity.

but as Patrick said, these accelerations have absolutely nothing to do with the forward acceleration of the plane.

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But if there is any tangential velocity of the wheel with respect to the conveyor belt, doesn't that mean that they are operating at different speeds?

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Velocity at what point on the wheel? The only meaningful points in this context are the wheel center and where the wheel contacts the conveyor. The velocity at the wheel center is the same as the plane's velocity. The velocity where the wheel contacts the conveyor is the same as the conveyor and the velocity's magnitude varies linearly between these two points. In the general case, they're not the same.

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Bro, you're claiming a car can travel 1 mile with respect to the ground while its wheels have only covered 3/4 mile.

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No. You are an absolute fool if you believe all the crap you've posted in this thread. Don't worry, though, I'll include this little concept in my fury.

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No one is arguing that a plane on a frictionless surface can take off. Try to remember this before you "own" me by showing this exact situation.

[NLSoldier]

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ok, now i only owe him $100 from that time i bet him $500 that noone was in the bathroom

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for those of you on hooded4's side. I'll clarify what kind of an idiot you are siding with.

Our friend and his brother are at our house. Naturally, they have the same last name. Friend goes in the bathroom, pees, exits, walks past us and goes outside. Brother walks in the bathroom and closes door. Hooded says wheres XXXXX?(refering to him by his last name). I say XXXXX is in the bathroom. He says no hes not I just saw him leave! So we bet $500, brother opens door and we see him leave the bathroom. PWNED.