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Title: Brainteaser: There's an airplane on the runway..
Source:
Elsewhere
URL Source: http://www.someplaceelse.com
Published: Dec 1, 2005
Author: I have no idea
Post Date: 2005-12-01 01:10:02 by Jhoffa_
Keywords: Brainteaser:, airplane, runway..
Views: 2056
Comments: 202
Imagine a plane is sat on the beginning of a massive conveyor belt/travelator type arrangement, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is no wind. Can the plane take off?
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Begin Trace Mode for Comment # 154.
#33. To: Jhoffa_ (#0)
Without reading too many of the responses so far, if I understand right, at whatever speed the plane begins to move forward, the conveyer belt moves backwards. Assuming the plane is propelled forward by jet or prop engines and not through a drive transmission to the wheels (which would not be a particularly well designed aircraft), then it won't stop the plane from going airborne. The only difference it would make is that the wheels would be spinning twice as fast at the airspeed when it takes off (which I'm assuming won't cause them to blow out, causing the plane to crash).
The only way the plane could take off is if it actually did move forward or up. Since the force of the engines is basically parallel with the ground then the only option is moving forward to become airborne. How does a multi-ton object become air born when it has no upward force being applied? The only way it could move forward is if it skidded down the runway and took off that way. I don't think they make planes capable of doing that, so it wouldn't take off. But if they had jet engines powerful enough and planes able to withstand the skidding, then it would take off.
Moving forward generates the lift required to climb, of course. Since the plane is not thrusting against the belt, but against the gases being expelled by the engine, it would accelerate. On further thought, though, the only way the plane could move forward is if the wheels turned fasted than the conveyor belt, and the operation of the belt would make that impossible. Ergo, as soon as thrust was applied, both the belt and the wheels would accelerate to an infinite speed, at which time the wheels, and probably the belt would both instantly explode, killing everyone and making the question moot. At that point the question would need to be redefined.
nope, the wheels and conveyer belt are none issues
For the sake if this question, yes they are. It is mathematically impossible that the plane could move forward while in contact with cvbelt, the landing gear wheels are in fact solidly attached to the airframe, and are only moving forward to compensate for the rearward movement of conveyor belt. It says so right at the top! :)
Are you mental?
Yeah, so what? Forget physics, in the world of this brain-teaser the cbelt has to achieve infinite speed to compensate. The wheels are spinning, they must be there...
#156. To: Dakmar (#154)
If you close your left eye and cycle the closing and opening of the right eye you can see Jesus....
Top • Page Up • Full Thread • Page Down • Bottom/Latest Can the plane take off?
#66. To: Neil McIver (#33)
Assuming the plane is propelled forward by jet or prop engines and not through a drive transmission to the wheels (which would not be a particularly well designed aircraft), then it won't stop the plane from going airborne. The only difference it would make is that the wheels would be spinning twice as fast at the airspeed when it takes off (which I'm assuming won't cause them to blow out, causing the plane to crash).
#111. To: RickyJ (#66)
How does a multi-ton object become air born when it has no upward force being applied? The only way it could move forward is if it skidded down the runway and took off that way.
#142. To: Neil McIver (#111)
the only way the plane could move forward is if the wheels turned fasted than the conveyor belt
#149. To: wakeup (#142)
nope, the wheels and conveyer belt are none issues
#150. To: Dakmar (#149)
It is mathematically impossible that the plane could move forward while in contact with cvbelt,
#154. To: timetobuildaboat (#150)
Are you mental?
Replies to Comment # 154. Forget physics, in the world of this brain-teaser the cbelt has to achieve infinite speed to compensate. The wheels are spinning, they must be there...
End Trace Mode for Comment # 154.