Imagine a plane is sitting on a treadmill...
Nov 14th 2007 | 1:04 pm
#79
Banned
Joined: Aug 2007
Posts: 1,810
From: New Caledonia
Re: Imagine a plane is sitting on a treadmill...
I think this is the key to the riddle. I got fixed on the treadmill negating the speed of the wheels. It's a semantic puzzle rather than a physics puzzle... if the planesis going at 100mph, the treadmill is going at -100mph. The wheels are going at 200mph.... but nonetheless the plane is going at 100mph. If the plane is moving it can take off.
Nov 14th 2007 | 2:03 pm
#82
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From: Markham ON Canada
Re: Imagine a plane is sitting on a treadmill...
Ignore wing lift for the moment and consider the plane to be a simple rocket in the horizontal position with wheels on the ground. Given the magic treadmill - it won't 'take off' BUT if the wheels are retracted it sure as hell will. So the same will apply to the plane, given it's at full engine thrust when the wheels are instantaneously retracted, the engine thrust must push the plane forward and so gain wing lift.
Nov 14th 2007 | 2:08 pm
#83
Joined: Oct 2004
Posts: 7,715
Re: Imagine a plane is sitting on a treadmill...
Ignore wing lift for the moment and consider the plane to be a simple rocket in the horizontal position with wheels on the ground. Given the magic treadmill - it won't 'take off' BUT if the wheels are retracted it sure as hell will. So the same will apply to the plane, given it's at full engine thrust when the wheels are instantaneously retracted, the engine thrust must push the plane forward and so gain wing lift.
Nov 14th 2007 | 2:12 pm
#84
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Joined: Apr 2005
Posts: 4,842
Re: Imagine a plane is sitting on a treadmill...
You're too far away for that, anyway, I'm glad you said shins.
And not chins.
And not chins.
Last edited by steve666; Nov 14th 2007 at 2:20 pm. Reason: added last sentence in case it was mis con strude
Nov 14th 2007 | 4:46 pm
#85
Thread Starter
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From: Newmarket, Ontario
Nov 14th 2007 | 10:02 pm
#86
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Posts: 142
From: Newmarket, Ontario
Nov 14th 2007 | 11:01 pm
#87
I'm a girl, dagnabbit! :)
Joined: Apr 2005
Posts: 1,120
From: Ottawa, ON.
Re: Imagine a plane is sitting on a treadmill...
After reading all this, I have a headache.
And I still have no idea whether the plane would take off or not.
And I'm late for work.
Hopefully my bus won't be on a treadmill...
And I still have no idea whether the plane would take off or not.
And I'm late for work.
Hopefully my bus won't be on a treadmill...
Nov 14th 2007 | 11:59 pm
#88
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Posts: 4,234
Re: Imagine a plane is sitting on a treadmill...
Switch the conveyor off and then watch that plane fly! doesnt that explain it?
Nov 15th 2007 | 12:45 am
#89
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Posts: 30,771
From: Upstate South Carolina
Re: Imagine a plane is sitting on a treadmill...
B: Engines are at full thrust...but dont forget momentum/inertia. Lift comes from airflow over the wing, not thrust from the engine.
C: The treadmill is irrelevent to the airspeed so its would be in the air anyway long before the undercarriage retracts.
Nov 15th 2007 | 1:47 am
#90
Lost in BE Cyberspace
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Posts: 5,430
From: Markham ON Canada
Re: Imagine a plane is sitting on a treadmill...
A: Instantaneously retracted? That would be a first...several tons of undercarriage takes a while to move
B: Engines are at full thrust...but dont forget momentum/inertia. Lift comes from airflow over the wing, not thrust from the engine.
C: The treadmill is irrelevent to the airspeed so its would be in the air anyway long before the undercarriage retracts.
B: Engines are at full thrust...but dont forget momentum/inertia. Lift comes from airflow over the wing, not thrust from the engine.
C: The treadmill is irrelevent to the airspeed so its would be in the air anyway long before the undercarriage retracts.
B. The airflow under the wings is generated by the treadmill moving at one hell of a speed - it must be dragging air along with it, unless its frictionless then we don't have a problem anyway as the plane would be on ice. So if the air is moving under the wing but not over it we have lift.
C. Wasn't the whole problem that the plane had no forward movement due to the treadmill moving at the same speed as the plane so how do you generate 'airspeed' - unless you accept B. above being airspeed and not the plane airspeed.
