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#311
11-23-2005, 04:48 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] [ QUOTE ] [ QUOTE ] thats the whole point of a treadmill, so you can run WITHOUT MOVING. [/ QUOTE ] Now throw rollerskates on and use the handles to pull yourself forward. [/ QUOTE ] I'm going to expand on this a little. Imagine you're on the treadmill, on roller skates with perfect bearings. Someone is controlling the speed of the treadmill for you, and they keep turning it up. Since you're on frictionless wheels, the speed of the treadmill doesn't affect you, right? Okay, grab hold of the handles now. Imagine that the dude keeps cranking up the speed on the treadmill. Is there any speed he could possibly turn it up to that could stop you from simply pulling yourself forward with the handles if you wanted to? [/ QUOTE ] people are going to say "but when you pull yourself forward, the wheels will be going faster than the treadmill" which is partially true [/ QUOTE ] They'd be wrong. The wheel center is moving at a different speed, but the surface in contact with the treadmill is not, assuming non-slip conditions (which we are). Do I have to draw a picture of this too, when I unleash my fury? [/ QUOTE ] Actually I would like to see this picture. The OP as stated, is not possible. It is not possible to have a runway moving at the same speed as the wheels if you are applying an outside force to the plane. 
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#312
11-23-2005, 04:49 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
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). [/ QUOTE ] I second this
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#313
11-23-2005, 04:51 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] 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. [/ QUOTE ] 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? [/ QUOTE ] 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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#314
11-23-2005, 04:52 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] 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). [/ QUOTE ] I second this [/ QUOTE ] 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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#315
11-23-2005, 04:53 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
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). [/ QUOTE ]
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#316
11-23-2005, 04:54 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
I mean seriously, he just said "I wasn't going to make you pay anyway." [/ QUOTE ] FWIW, I told some people on aim long ago that I had no intentions of taking half of my friends bankroll from him. Im just waiting for him to admit hes wrong.
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#317
11-23-2005, 04:54 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] 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). [/ QUOTE ] I second this [/ QUOTE ] 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." [/ QUOTE ] NLsoldier owes you $400 because the situation is theoretically impossible.
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#318
11-23-2005, 04:55 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] [ QUOTE ] I'm going to agree with goofball. According to the phrasing of the OP, the plane is not moving. It's not that the plane is stationary because the plane is like a car and thrust by its wheels, nor because it's physically impossible for the plane to move relative to the ground/air when on a conveyor belt, but rather, the plane is stationary because that's how the problem has been defined. If the plane moves forward any amount relative to the ground such that lifting off would become possible, the criteria laid out in the OP (wheels movement = conveyor movement) is no longer met. This is not about aerospace engineering, rather so much as it is about reading comprehension (or more precisely, poor phrasing in the original post). [/ QUOTE ] I second this [/ QUOTE ] This is exactly correct, and as a side note, I'm sitting right next to NLSoldier, and when he saw this, he said "Don't worry, Pat will come back on and pwn him in a sec!" Somone tell that donk he owes me 400$....I mean seriously, he just said "I wasn't going to make you pay anyway." [/ QUOTE ] NLsoldier owes you $400 because the situation is theoretically impossible. [/ QUOTE ] the situation being "plane lifting off"
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#319
11-23-2005, 04:56 PM
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Re: think about this...
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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#320
11-23-2005, 04:56 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] 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. [/ QUOTE ] 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? [/ QUOTE ] 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. [/ QUOTE ] 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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