Plane on conveyer: Will it ever take off?
Former Moderator
Joined: Oct 2000
Posts: 16,175
Likes: 0
From: Erock is da shizzle
That's a great explanation, not that I'm trying to argue it, as I answered on the first page, but I'll admit I wasn't really thinking of the friction constant, my initial thought is that at some point friction will increase, ya, due to heat, etc. but forgiving that for the sake of the argument, indeed it would have no bearing on this riddle.
Registered User
Joined: Jul 2003
Posts: 7,840
Likes: 1
From: socal
i thought airplane wings were designed to create a low pressure zone above the wing and high pressure below the wing, thereby causing lift. How can it do this if there is no air flowing over or under the wing? Also, assuming the plane does take off, when does it gain forward momentum? would it bolt like a bottle rocket? or would it just touch back down in the same spot?
I think the plane wont fly.
I think the plane wont fly.
Registered User
Joined: Jul 2003
Posts: 7,840
Likes: 1
From: socal
Originally Posted by Tedow,Dec 1 2005, 06:02 PM
Actually, yes it will. The trick is that the plane's engines are not pushing against the ground, as a car would. The force comes from the air, so the plane moves forward as usual...the presence of the moving ground plane is completely irrelevant. Well, okay, the plane's wheels will spin twice as fast as usual, but that's all. Plane takes off.
Registered User
Joined: Jul 2003
Posts: 7,840
Likes: 1
From: socal
Originally Posted by Gink5,Dec 2 2005, 01:35 PM
To add, there are two major forces on the plane. One gravity pushing down and two the thrust from the engines which is horizontal. The conveyer belt doesnt add a force to the plane in the opposite direction(which is the trick) The only force presented to the plane from the conveyer belt is the force of friction between the wheel and conveyer surface. Now the plane would not take off if the wheels were lets say glued(not the best example but you get the idea), this would increase the friction enough to keep the plane from moving.
Registered User
Joined: Jul 2003
Posts: 7,840
Likes: 1
From: socal
i dunno if this is a good example or not, but:
If you have a helicopter whos blades spin at 2000 rpm clockwise, and it flies into the center of a tornado also spinning at 2000 rpm clockwise, wouldnt the helicopter fall because the blades are not moving relative to the air its supposed to be pushing against??
Same thing with the plane. its wings are not pushing against the air.
If you have a helicopter whos blades spin at 2000 rpm clockwise, and it flies into the center of a tornado also spinning at 2000 rpm clockwise, wouldnt the helicopter fall because the blades are not moving relative to the air its supposed to be pushing against??
Same thing with the plane. its wings are not pushing against the air.
Registered User
Joined: Jan 2004
Posts: 966
Likes: 0
From: San Francisco Bay Area
Originally Posted by r_duff,Dec 2 2005, 03:21 PM
assuming you have to have airflow (air pushing against the wings) to create lift, the conveyer belt is effectively negating the thrust provided by the engines, thus negating airflow... right??!
the plane gains lift by gaining speed. If that "speed" part of the equation is taken away by the conveyor, then you get no lift. The wheels will be in constant contact with the conveyor since there is no lift on the plane.
Registered User
Joined: Jul 2003
Posts: 7,840
Likes: 1
From: socal
this is the pressing question in my mind for all u who say it will take off:
Also, assuming the plane does take off, when does it gain forward momentum? would it bolt like a bottle rocket? or would it just touch back down in the same spot?
Also, assuming the plane does take off, when does it gain forward momentum? would it bolt like a bottle rocket? or would it just touch back down in the same spot?
