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Thread Statistics | Show CCP posts - 2 post(s) |
Mr Adequate
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Posted - 2005.12.05 03:36:00 -
[31]
OP and Thomus, you're both wrong.
The plane WILL take off.
Thrust generated by the jet engines moves the plane forward, irrespective of the undercarriages wheels revolutions. All that would happen is the wheels would be spinning twice as fast as normal when the plane takes off. It doesn't matter what holds the plane up, it's the jet engines that move the plane forward, not the wheels underneath. Taking the analogy of walking on a travellator in the wrong direction is flawed, as people draw their propulsion from friction with the ground, whereas a plane does not.
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Baldour Ngarr
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Posted - 2005.12.05 05:01:00 -
[32]
*sigh*
Plane fires jets = propulsion forwards.
Conveyor belt spinning in opposite direction = propulsion backwards.
Net movement = zero.
"I tried strip mining, but I lost, and it's cold flying around in space naked." |
My grandfather
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Posted - 2005.12.05 05:10:00 -
[33]
Edited by: My grandfather on 05/12/2005 05:10:50
 Originally by: Baldour Ngarr
*sigh*
Plane fires jets = propulsion forwards.
Conveyor belt spinning in opposite direction = propulsion backwards.
Net movement = zero.
Wrong.
Plane fires jets = propulsion forwards on the entire plane.
Conveyor belt spinning in opposite direction = wheels on the plane spinning faster, meaning a bit extra friction, but they still roll.
Net movement = plane moving forward.
Think of it like someone riding a bike on a conveyor belt. No matter how hard he pedals, he stays still. But if you give him a push in the back he WILL move forward.
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Mr Adequate
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Posted - 2005.12.05 05:13:00 -
[34]
Cheers Grandfather, couldn't put it better myself, thanks.
The main point is that the planes forward momentum is completely independant of its interaction with the ground.
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My grandfather
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Posted - 2005.12.05 05:22:00 -
[35]
Originally by: Mr Adequate
The main point is that the planes forward momentum is completely independant of its interaction with the ground.
voila. Basic high school fysics ftw! 
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Baldour Ngarr
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Posted - 2005.12.05 09:35:00 -
[36]
Originally by: My grandfather
Think of it like someone riding a bike on a conveyor belt. No matter how hard he pedals, he stays still. But if you give him a push in the back he WILL move forward.
You're assuming that the conveyor belt does not alter in speed; which is not the basis of the original question. If the belt's moving backwards at the same speed as the plane is trying to move forwards, net velocity *IS* zero.
"I tried strip mining, but I lost, and it's cold flying around in space naked." |
Thomus
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Posted - 2005.12.05 09:44:00 -
[37]
wrt to the last few posts, i realise i was wrong, the plane will move
Baldour, i did physics A-level, which in England is more physics than most people will ever do. Now i have realised that the engines are exerting a force on the plane by pushing it thru the air.
The wheels are free to move, and in an ideal world, should have no resistance at all. The fact that the ground is moving will only make the wheels spin. If the engines are pumping out enough force to move the plane, it will move, irrespective of the ground.
IF this was a question about a truck on a moving belt, the truck is using the WHEELS to exert a force on the ground in order to propel the truck forwards. however, in this case, the belt moving in the same direction as the force that the wheels are exerting, will cause the truck to not move.
The PLANE WILL move, a TRUCK in the same circumstances WON'T MOVE.
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Tom |
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