Will the Plane Take-Off - Merged with MythBusters Show Thread
02-02-2008, 01:56 PM
#961
Senior Moderator
02-02-2008, 03:25 PM
#963
Interesting. Interesting.
Originally Posted by crazymjb
Well actually as long as the treadmill was INSTANTLY matching the wheel speed it couldn't take off. This is because if the plane is sitting still on the treadmill moving 10MPH, the wheels are moving 10MPH. As soon as the plane starts to move against the treadmill, the wheel speed = 10MPH+speed the plane is moving. The problem is the treadmill would then need to instantly be at the new wheel speed. At the same time, the wheel speed would have to equal the "new" wheel speed, plus the speed the treadmill is moving forward. So the key word is Instant, and the wheel speed could not mathematically be matched.
Assuming Y>0 and X>0, X Cannot = X+Y
However, since the treadmill matches the AIR SPEED, the wheels will just spin twice as fast.
Mike
Assuming Y>0 and X>0, X Cannot = X+Y
However, since the treadmill matches the AIR SPEED, the wheels will just spin twice as fast.
Mike
I weep for the marines.
02-02-2008, 03:29 PM
#965
Go Giants
Originally Posted by srika
02-02-2008, 03:49 PM
#968
Go Giants
^^Where hell is the treadmill 
02-02-2008, 04:06 PM
#970
Go Giants
Originally Posted by Dan Martin
Assume one horse is running in the opposite direction...
02-02-2008, 04:07 PM
#971
Originally Posted by wstevens
oof. the wheels are passive - they can spin as much as they want and not affect the movement of the airplane. Why don't you think this is the case?
I weep for the marines.
I weep for the marines.
Say you are holding a toy car on a treadmill. The wheels are spinning 10MPH as well as the belt which is spinning 10MPH in the other direction. The condition is the belt MUST be instantly matched to the wheel speed. You go to push the wheel 5MPH opposite the direction of the belt. That would make the wheel speed 15MPh. No problem right, the belt just needs to move 15MPH... WRONG If the belt starts moving 15 MPH the wheel will be moving 20MPH. Since the belt needs to reach the wheel speed INSTANTIOUSLY, it is not possible to move the wheel in the opposite direction of belt rotation. For that reason, if those THEORETICAL conditions were being met, no matter what source of propulsion the plane could not move forward (because time would stop or the earth would be turned inside out or some strange shit like that).
But since the myths says the belt speed is matching the AIR SPEED relative to stationary ground, the only thing that will happen is the plane will take off with the wheels spinning twice as fast.
Mike
02-02-2008, 04:12 PM
#972
Interesting. Interesting.
Originally Posted by crazymjb
You are absolutely right, wheels are passive. HOWEVER, in that situation, the wheels would be required to spin at a speed not that was too fast for them, but that mathamatically would not be possible. It is a physics/math problem unrelated to the rest of the aircraft. In fact, you could get rid of the plane all together.
Mike
Mike
02-02-2008, 04:15 PM
#973
Interesting. Interesting.
Also, in your example, what do you mean by the wheel spinning at 10 MPH? what part of the wheel? The part of the wheel that is instantaneously in contact with the treamill has zero velocity relative to the treadmill (assuming the wheel is rolling, not skidding).
02-02-2008, 04:20 PM
#974
fuck the plane! Same goes for treadmills! 
02-02-2008, 04:21 PM
#975
Interesting. Interesting.
Remember, we agreed that the wheels are passive. So, the angular velocity at which they are spinning is independent of the linear velocity that the axle is moving. When you say the wheels are "spinning" at 10 MPH, it doesn't make sense. 10 MPH doesn't have the right units for angular velocity.
02-02-2008, 04:56 PM
#978
I am saying when I first saw it, I thought it was a trick question. Now that I know it is not, I know it is not...
What I was trying to say is as follows. If you rest a wheel on a treadmill with a tachometer connected to it and run the treadmill, at 10MPH, then multiply the RPM by circumfrence the wheel will be spinning at 10MPH. Now if you move the wheel "assembly" in the opposite direction of which the belt is spinning, and again multiply RPM times circumfrence, you will get 10MPH + X.
Now if the conditions of the original "myth" were that the belt had to instantaneously be matched to the wheel speed, it would not be possible to have a situation as such with the wheel assembly in motion relative to a fixed point (not the treadmill belt) and counter to the direction of the treadmill belt.
Mike
What I was trying to say is as follows. If you rest a wheel on a treadmill with a tachometer connected to it and run the treadmill, at 10MPH, then multiply the RPM by circumfrence the wheel will be spinning at 10MPH. Now if you move the wheel "assembly" in the opposite direction of which the belt is spinning, and again multiply RPM times circumfrence, you will get 10MPH + X.
Now if the conditions of the original "myth" were that the belt had to instantaneously be matched to the wheel speed, it would not be possible to have a situation as such with the wheel assembly in motion relative to a fixed point (not the treadmill belt) and counter to the direction of the treadmill belt.
Mike
02-02-2008, 05:07 PM
#979
Interesting. Interesting.
Originally Posted by bigman
The plane moves in one direction, while the conveyer moves in the opposite
direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite
direction).The question is:Will the plane take off or not?
.
direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite
direction).The question is:Will the plane take off or not?
.
02-02-2008, 06:38 PM
#985
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02-06-2008, 08:14 AM
#987
THE PLANE TAKES OFF!!!!!
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Originally Posted by crazymjb
You are absolutely right, wheels are passive. HOWEVER, in that situation, the wheels would be required to spin at a speed not that was too fast for them, but that mathamatically would not be possible. It is a physics/math problem unrelated to the rest of the aircraft. In fact, you could get rid of the plane all together.
Say you are holding a toy car on a treadmill. The wheels are spinning 10MPH as well as the belt which is spinning 10MPH in the other direction. The condition is the belt MUST be instantly matched to the wheel speed. You go to push the wheel 5MPH opposite the direction of the belt. That would make the wheel speed 15MPh. No problem right, the belt just needs to move 15MPH... WRONG If the belt starts moving 15 MPH the wheel will be moving 20MPH. Since the belt needs to reach the wheel speed INSTANTIOUSLY, it is not possible to move the wheel in the opposite direction of belt rotation. For that reason, if those THEORETICAL conditions were being met, no matter what source of propulsion the plane could not move forward (because time would stop or the earth would be turned inside out or some strange shit like that).
But since the myths says the belt speed is matching the AIR SPEED relative to stationary ground, the only thing that will happen is the plane will take off with the wheels spinning twice as fast.
Mike
Say you are holding a toy car on a treadmill. The wheels are spinning 10MPH as well as the belt which is spinning 10MPH in the other direction. The condition is the belt MUST be instantly matched to the wheel speed. You go to push the wheel 5MPH opposite the direction of the belt. That would make the wheel speed 15MPh. No problem right, the belt just needs to move 15MPH... WRONG If the belt starts moving 15 MPH the wheel will be moving 20MPH. Since the belt needs to reach the wheel speed INSTANTIOUSLY, it is not possible to move the wheel in the opposite direction of belt rotation. For that reason, if those THEORETICAL conditions were being met, no matter what source of propulsion the plane could not move forward (because time would stop or the earth would be turned inside out or some strange shit like that).
But since the myths says the belt speed is matching the AIR SPEED relative to stationary ground, the only thing that will happen is the plane will take off with the wheels spinning twice as fast.
Mike
The equation with the "match the wheels speed" is obviously improbably and impossible, because you couldn't get a treadmill to spin that fast, or wheels that would hold up to speeds that they would reach.
Other people in here are still thinking we're discussing the "original" theoretical question, and "not getting it"... lol
02-06-2008, 02:14 PM
#988
So formulaically speaking, where x is the speed of the wheel and treadmill: x-x=0 (x speed forward minus x speed backward equals zero difference), but (x+5)-(x-5)<>0 (x speed plus five extra speed units minus x speed backwards plus five extra speed units backwards [expressed as a negative value] cannot equal a zero difference)? Makes sense to me.
02-06-2008, 05:05 PM
#990
Team Owner
You guys are still not taking into account the air traffic controllers.
Unhinge your mind, the plane's wheels are not drive wheels. The ability of the plane to move forward and cause airflow under the wings is in no way dependent on how fast the wheels spin.
Unhinge your mind, the plane's wheels are not drive wheels. The ability of the plane to move forward and cause airflow under the wings is in no way dependent on how fast the wheels spin.
02-06-2008, 05:32 PM
#991
Originally Posted by jlukja
You guys are still not taking into account the air traffic controllers.
Unhinge your mind, the plane's wheels are not drive wheels. The ability of the plane to move forward and cause airflow under the wings is in no way dependent on how fast the wheels spin.
Unhinge your mind, the plane's wheels are not drive wheels. The ability of the plane to move forward and cause airflow under the wings is in no way dependent on how fast the wheels spin.
02-07-2008, 08:15 AM
#992
THE PLANE TAKES OFF!!!!!
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Originally Posted by jlukja
You guys are still not taking into account the air traffic controllers.
Unhinge your mind, the plane's wheels are not drive wheels. The ability of the plane to move forward and cause airflow under the wings is in no way dependent on how fast the wheels spin.
Unhinge your mind, the plane's wheels are not drive wheels. The ability of the plane to move forward and cause airflow under the wings is in no way dependent on how fast the wheels spin.
Myself and a few others are now talking about the fact that if the treadmill matched the planes WHEEL-SPEED and not the plane's actual forward speed.... that it wouldn't take off.
02-07-2008, 08:56 AM
#993
Make MyTL Great Again
Okay so let me put my 
suit on first.
I've watched the mythbusters episode.
It still doesn't make sense to me. For the plane to move forward, it's propeller must make the plane move which would cause it's un-propelled wheels to move in the same direction of the plane.
However, if the propeller on the plane is causing the plane to move forward (even on a normal runway), the wheels are going to wind up spinning at the same speed that the plane is advancing forward.
So if the plane is on this treadmill, and the plane is advancing forward (as it did on the show), then the treadmill speed is not matching the speed of the plane. If the speeds were matched it shouldn't move at all.
The plane needs to move forward to get wind over the wings (I think we can all agree).
Am I wrong that the wheels of the plane wind up going the same speed at the whole plane itself (caused by the propeller)? If I am, then what speed do the wheels move at in relation to the rest of the plane?
suit on first.I've watched the mythbusters episode.
It still doesn't make sense to me. For the plane to move forward, it's propeller must make the plane move which would cause it's un-propelled wheels to move in the same direction of the plane.
However, if the propeller on the plane is causing the plane to move forward (even on a normal runway), the wheels are going to wind up spinning at the same speed that the plane is advancing forward.
So if the plane is on this treadmill, and the plane is advancing forward (as it did on the show), then the treadmill speed is not matching the speed of the plane. If the speeds were matched it shouldn't move at all.
The plane needs to move forward to get wind over the wings (I think we can all agree).
Am I wrong that the wheels of the plane wind up going the same speed at the whole plane itself (caused by the propeller)? If I am, then what speed do the wheels move at in relation to the rest of the plane?
02-07-2008, 09:02 AM
#994
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Originally Posted by Converted
We're on a different situation now.... we all know given the ORIGINAL arguement, that it takes off...
Myself and a few others are now talking about the fact that if the treadmill matched the planes WHEEL-SPEED and not the plane's actual forward speed.... that it wouldn't take off.
Myself and a few others are now talking about the fact that if the treadmill matched the planes WHEEL-SPEED and not the plane's actual forward speed.... that it wouldn't take off.
The special thing with wheels, however, is that linear velocity of an ideal wheel (i.e. no slippage) at the point of contact with respect to the surface of travel is always zero. So in the scenario that you mention above, the treadmill speed would have to be zero, and the plane would take off.
Really, though, the problem with the question as you pose it is that it's not even close to specific enough. And frankly, that's because you have no clue what you're talking about (regarding simple physics like this).
02-07-2008, 09:19 AM
#995
THE PLANE TAKES OFF!!!!!
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Originally Posted by AdamNJ
Okay so let me put my suit on first.
I've watched the mythbusters episode.
It still doesn't make sense to me. For the plane to move forward, it's propeller must make the plane move which would cause it's un-propelled wheels to move in the same direction of the plane.
However, if the propeller on the plane is causing the plane to move forward (even on a normal runway), the wheels are going to wind up spinning at the same speed that the plane is advancing forward.
So if the plane is on this treadmill, and the plane is advancing forward (as it did on the show), then the treadmill speed is not matching the speed of the plane. If the speeds were matched it shouldn't move at all.
The plane needs to move forward to get wind over the wings (I think we can all agree).
Am I wrong that the wheels of the plane wind up going the same speed at the whole plane itself (caused by the propeller)? If I am, then what speed do the wheels move at in relation to the rest of the plane?
suit on first.I've watched the mythbusters episode.
It still doesn't make sense to me. For the plane to move forward, it's propeller must make the plane move which would cause it's un-propelled wheels to move in the same direction of the plane.
However, if the propeller on the plane is causing the plane to move forward (even on a normal runway), the wheels are going to wind up spinning at the same speed that the plane is advancing forward.
So if the plane is on this treadmill, and the plane is advancing forward (as it did on the show), then the treadmill speed is not matching the speed of the plane. If the speeds were matched it shouldn't move at all.
The plane needs to move forward to get wind over the wings (I think we can all agree).
Am I wrong that the wheels of the plane wind up going the same speed at the whole plane itself (caused by the propeller)? If I am, then what speed do the wheels move at in relation to the rest of the plane?
Plus, the Mythbusters just made it even MORE stupid, and said the treadmill was only going the planes "Take-off" speed... so although the plane was going forward at 25MPH (take off speed) the wheels were spinning at 50MPH...
I mean, technically you could have the wheels spinning at 300MPH, and the plane would still take off.... the wheels have NO EFFECT on the plane moving through the air.
02-07-2008, 09:23 AM
#997
Senior Moderator
Originally Posted by Converted
Myself and a few others are now talking about the fact that if the treadmill matched the planes WHEEL-SPEED and not the plane's actual forward speed.... that it wouldn't take off.
Originally Posted by Converted
I mean, technically you could have the wheels spinning at 300MPH, and the plane would still take off.... the wheels have NO EFFECT on the plane moving through the air.
You sound confused.
02-07-2008, 09:28 AM
#998
THE PLANE TAKES OFF!!!!!
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Originally Posted by Hojo061782
But see, that's a completely absurd question. Wheel speed is measured in one way: angular velocity (radians/second or degrees/second). It's true that you can convert this angular velocity to a linear velocity, but only with respect to one point on the wheel.
The special thing with wheels, however, is that linear velocity of an ideal wheel (i.e. no slippage) at the point of contact with respect to the surface of travel is always zero. So in the scenario that you mention above, the treadmill speed would have to be zero, and the plane would take off.
Really, though, the problem with the question as you pose it is that it's not even close to specific enough. And frankly, that's because you have no clue what you're talking about (regarding simple physics like this).
The special thing with wheels, however, is that linear velocity of an ideal wheel (i.e. no slippage) at the point of contact with respect to the surface of travel is always zero. So in the scenario that you mention above, the treadmill speed would have to be zero, and the plane would take off.
Really, though, the problem with the question as you pose it is that it's not even close to specific enough. And frankly, that's because you have no clue what you're talking about (regarding simple physics like this).
It's apparent you think you're way smarter than you actually are... lol
DISCLAIMER: This is a NEW situation I'm reffering to, not the original question, for those just joining us
I'll break it down in simple 2nd-grader math for you...
Wheel (not plane) moves forward 5 MPH + Treadmill moving backward 5MPH = 0 relative forward speed
Wheel (not plane) moves forward 50MPH + Treadmill moving backward 50MPH = 0 relative forward speed
This differs from the original equation, which uses the PLANES SPEED, not the wheels, and looks like this:
Plane (not wheels) moves forward 25MPH + treadmill moving backwards at 25MPH = Wheels spin at 50MPH = (to match the planes speed) = 25MPH relative forward movement (the difference between the matched speed, and the actual wheel speed) = take-off
In that situation you can input ANY wheel speed, and it will have no effect on take-off... unlike the above equation, where we're talking about matching wheel speed directly, it will always match it, and always have zero forward travel.
You apparently aren't getting it... and I really can't "dumb it down" any more than that...
02-07-2008, 09:29 AM
#1000
THE PLANE TAKES OFF!!!!!
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Originally Posted by dom
You sound confused.