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#221
11-23-2005, 03:47 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
this thread is seriously the bomb. let's think a little about OP's original statement, that the conveyor belt is moving in the opposite direction as the wheels on the plane. now imagine the plane is completely turned off, there is 0 thrust from the turbines/props. The conveyor belt is moving backwards at 100 feet/sec. The planes wheels are spinning forwards at the same rate. The plane is standing still, no?? now what happens when you turn on the turbines and start generating forward thrust, WTF do you think the plane is going to do??? [/ QUOTE ] The plane is going to move forward and take off. But once that happens, the wheels are now moving faster than the conveyor, no? That's the only part I question. 
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#222
11-23-2005, 03:47 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] Explain how the wheels will move at the same speed as the plane in this example. [/ QUOTE ] THIS JUST IN: WHEELS ARE ATTACHED TO THE PLANE [/ QUOTE ] LOL, you're really not thinking hard enough.
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#224
11-23-2005, 03:49 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] [ QUOTE ] [ QUOTE ] [ QUOTE ] [ QUOTE ] Of course the plane has to be moving relative to the air around it (or the ground if that makes it easier). [/ QUOTE ] this is it, you need wind over the wings for lift!! a plane cannot get in the air without lift! wtf, i can't believe noone gets this [/ QUOTE ] Please explain specifically what FORCE is stopping the plane from moving forward (relative to the atmosphere, NOT the conveyor belt). [/ QUOTE ] Uh. The conveyor belt moves at the same speed as the wheels as stated in the problem. Thus the plane cannot move forward. Seriously how much physics do you understand? Are you familiar with reference frames? [/ QUOTE ] Explain how the wheels will move at the same speed as the plane in this example. [/ QUOTE ] THIS JUST IN: WHEELS ARE ATTACHED TO THE PLANE [/ QUOTE ] dude, one sec. if the plane's velocity is 100 mph in the +x direction and the conveyor's velocity is 100 mph in the -x direction (and the turbines are off), we agree that the plane is not moving relative to the ground, correct? now what happens if you apply a force to the plane in the +x direction? is it locked in space? can it not move? [/ QUOTE ] Yeah I totally agree with you here. The thing is, as stated in the original problem, the runway speeds up to compensate for the extra +x force.
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#225
11-23-2005, 03:50 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] dude, one sec. if the plane's velocity is 100 mph in the +x direction and the conveyor's velocity is 100 mph in the -x direction (and the turbines are off), we agree that the plane is not moving relative to the ground, correct? now what happens if you apply a force to the plane in the +x direction? is it locked in space? can it not move? [/ QUOTE ] Yeah I totally agree with you here. The thing is, as stated in the original problem, the runway speeds up to compensate for the extra +x force. [/ QUOTE ] and the wind does too???
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#226
11-23-2005, 03:50 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] [ QUOTE ] [ QUOTE ] [ QUOTE ] Of course the plane has to be moving relative to the air around it (or the ground if that makes it easier). [/ QUOTE ] this is it, you need wind over the wings for lift!! a plane cannot get in the air without lift! wtf, i can't believe noone gets this [/ QUOTE ] Please explain specifically what FORCE is stopping the plane from moving forward (relative to the atmosphere, NOT the conveyor belt). [/ QUOTE ] Uh. The conveyor belt moves at the same speed as the wheels as stated in the problem. Thus the plane cannot move forward. Seriously how much physics do you understand? Are you familiar with reference frames? [/ QUOTE ] Explain how the wheels will move at the same speed as the plane in this example. [/ QUOTE ] THIS JUST IN: WHEELS ARE ATTACHED TO THE PLANE [/ QUOTE ] You do realize that a plane's wheels spin freely like a car in neutral not a car in gear, right?
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#227
11-23-2005, 03:51 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] this thread is seriously the bomb. let's think a little about OP's original statement, that the conveyor belt is moving in the opposite direction as the wheels on the plane. now imagine the plane is completely turned off, there is 0 thrust from the turbines/props. The conveyor belt is moving backwards at 100 feet/sec. The planes wheels are spinning forwards at the same rate. The plane is standing still, no?? now what happens when you turn on the turbines and start generating forward thrust, WTF do you think the plane is going to do??? [/ QUOTE ] The plane is going to move forward and take off. But once that happens, the wheels are now moving faster than the conveyor, no? That's the only part I question. [/ QUOTE ] no they're not. that is impossible per the OP. the thrust is exerted against the air not against the runway, so the thrust from the turbines vs. surrounding air is orthogonal to runway vs. wheels
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#228
11-23-2005, 03:52 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
The thing is, as stated in the original problem, the runway speeds up to [/ QUOTE ] Wait, you understand this point and still think it can't take off? Holy hell. Edited for clarity
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#229
11-23-2005, 03:52 PM
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Re: Physics graduate from Daryn\'s alma mater\'s answer
[ QUOTE ]
[ QUOTE ] [ QUOTE ] dude, one sec. if the plane's velocity is 100 mph in the +x direction and the conveyor's velocity is 100 mph in the -x direction (and the turbines are off), we agree that the plane is not moving relative to the ground, correct? now what happens if you apply a force to the plane in the +x direction? is it locked in space? can it not move? [/ QUOTE ] Yeah I totally agree with you here. The thing is, as stated in the original problem, the runway speeds up to compensate for the extra +x force. [/ QUOTE ] and the wind does too??? [/ QUOTE ] the [censored] does that matter
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#230
11-23-2005, 03:52 PM
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Re: think about this...
[ QUOTE ]
[ QUOTE ] [ QUOTE ] It's very much like a float plane taking off from the water (where there's also negligible friction). [/ QUOTE ] No it is not. It would be like a float plane taking off from a river that is moving at an opposite speed of the floats. WOULD NOT TAKE OFF To simplify: 1. Plane on a runway. Takes off 2. Plane with locked wheels on ice. Takes off. 3. Plane with locked wheels on runway. Doesn't take off. Note that #3 is the same problem that OP phrased. [/ QUOTE ] Quit trolling.
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