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MythBusters tackles "plane on a conveyor belt problem"


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#316 vetFred Derf

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Posted 31 January 2008 - 12:44

No, that's what I mean. Like I said, I took the conveyor belt to be a way of saying "the plane is stationary on the ground". So the engines are at full force, but the plane isn't moving forward. That's how I (and many others) interpreted the question and in THAT scenario, the plane definitely would not take off.

Yes, you got caught in that trap. That is the trap for the people who think of a plane as a winged car.

The people who understood that a plane was not a winged car knew that the plane would go forward.


#317 Kushan

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Posted 31 January 2008 - 12:45

Yes, they knew it would go forward, but that never even factored into it for me and many others. Read what I'm saying, I interpreted the conveyor to just be a way of keeping the plane stationary, nothing more. It may as well have said "an anti-gravity field is placed upon the plane to prevent it moving forward" for all I cared.

#318 vetFred Derf

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Posted 31 January 2008 - 12:45

...except that I didn't, because I know it's absolutely nothing like a car...

Yet you thought it would remain stationary.

#319 OP The_Decryptor

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Posted 31 January 2008 - 12:49

The question never stated the plane can't move, it asks if the plane could fly if the tread mill matches it's speed (and it doesn't say what speed, air speed, ground speed, what part of the plane, etc.)

#320 sundayx

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Posted 31 January 2008 - 12:50

Chat more?

#321 kernatch

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Posted 31 January 2008 - 13:37

interpreted the conveyor to just be a way of keeping the plane stationary


How could you interpret it that way and NOT be exactly the type of person this question was trying to catch out?

I've never seen someone try to make so many excuses about getting a trick question wrong. Deal with it! It's meant to be light hearted!

#322 Kushan

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Posted 31 January 2008 - 13:44

Yet you thought it would remain stationary.


No, I thought the question stated it would be stationary, there's a big difference.

#323 Lt-DavidW

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Posted 31 January 2008 - 14:01

It may be easier for some people to visualise the physics if they imagine the plane having frictionless pads in place of wheels and sat upon slippery ice. The plane's contact with the ground has little influence on the thrust driving the plane forward.

Wheels do not anchor planes to conveyor belts...

#324 vetFred Derf

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Posted 31 January 2008 - 14:46

No, I thought the question stated it would be stationary, there's a big difference.

I don't really see a difference. If you understand how a plane works then you would know that it would not be possible to stay stationary.

I initially made the same mistake (if you look at my first post in this thread) but I quickly caught on and accepted that I was wrong.

#325 Kushan

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Posted 31 January 2008 - 14:48

I don't really see a difference. If you understand how a plane works then you would know that it would not be possible to stay stationary.

I initially made the same mistake (if you look at my first post in this thread) but I quickly caught on and accepted that I was wrong.


What I'm saying is that I thought the question was saying "the plane is stationary, what happens?" and not "will the plane BE stationary?". I thought the focus of the question was on how flight works and not on how ground force affects planes.

#326 kernatch

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Posted 31 January 2008 - 14:55

I thought the focus of the question was on how flight works and not on how ground force affects planes.


Yep, and you were wrong to do so; the entire point of the question was to trick some people into thinking exactly that. Do you think you can deal with the fact you were wrong yet?

#327 vetFred Derf

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Posted 31 January 2008 - 14:56

What I'm saying is that I thought the question was saying "the plane is stationary, what happens?" and not "will the plane BE stationary?". I thought the focus of the question was on how flight works and not on how ground force affects planes.

Which is why other people, ones who completely understand how a plane works, did not accept that the plane would remain stationary. They concluded that the plane would move forward and thus that the plane would take off. You, on the other hand, got caught in the trap for lay people.

#328 Kushan

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Posted 31 January 2008 - 15:04

So really, the focus of the question was to see if people got caught or not and has nothing to do with planes?

If even pilots get the answer wrong, I think it proves that the question is poorly worded, a trick question even.

#329 +StevoFC

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Posted 31 January 2008 - 15:08

The fact the pilot kept saying he thought the plane would "sit there like a brick" made me realize that the guy had no idea what he was even talking about. It was, and still is, so obvious that the plane would still take off. Anyone who knows anything about how planes work could tell you that.

It doesn't matter how the damn question was worded. It flies...simple as that.

#330 Menge

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Posted 31 January 2008 - 15:10

So really, the focus of the question was to see if people got caught or not and has nothing to do with planes?

If even pilots get the answer wrong, I think it proves that the question is poorly worded, a trick question even.

i don't think the question was badly worded nor that it's a trick question. nowhere in the question does it say that the plane will be stationary:

"A plane is standing on a runway that can move (some sort of band conveyer). 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 the opposite direction). Can the plane take off?"

the answer is pretty obvious to anyone who:
1) knows how a plane moves
2) knows the three laws of newton



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