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| james |
 Feb 23 2006, 01:08 PM
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#1
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  Group: Super Administrators Posts: 3296 Joined: 2-March 01 From: Surrey, UK Member No.: 13  |
Here's a question for you:
QUOTE "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?" A couple of links discussing it (and some funny rationalizations for peoples incorrect assumptions): www.kottke.org/06/02/plane-conveyor-belt www.straightdope.com/columns/060203.html -------------------- "We are number one, all others are number two or lower!" - The Sphinx, Mystery Men
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| Emily |
Feb 24 2006, 03:57 PM
Post
#2
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 [Ringer Patrol]  Group: [Ringer Patrol] Posts: 717 Joined: 21-May 01 From: Old Woking, Surrey Member No.: 26 |
i cant even think if a way to explain it but as i've just said a car uses propulsion through the wheels, pushing the ground away, the plane used the air.
imagine you have wheels, and you have a big rope in front of you (the rope is the air) if you pull yourself along the rope it doesn't matter how fast the conveyer is going you will move along the rope, the wheels will just spin faster to keep up with you even if the conveyer spins faster too. you plane is taking air from the front and putting it behind itself in the same way you pull in the rope and push it away behind you apologies to james, its hard to explain and i didn't understand  -------------------- its all fun and games till somebody looses and eye!
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Posts in this topic
james Brainteaser Feb 23 2006, 01:08 PM
camsmith Before I look up the links... Yes it can. Feb 23 2006, 01:21 PM james Anyone else? Feb 23 2006, 02:07 PM paul My initial thought is a big no! I can explain... Feb 23 2006, 03:33 PM james Fire away! - Show your workings out and the ex... Feb 23 2006, 04:39 PM womble erm quick change of mind after new logical suggest... Feb 23 2006, 04:52 PM camsmith OK... My very first thought was no, but then I t... Feb 23 2006, 04:57 PM womble hmmm yeah that actually sounds about it yeah that ... Feb 23 2006, 05:14 PM james Yeah that's exactly it - I think what makes us... Feb 23 2006, 05:25 PM Sam This is Paul - Can't be arsed to log out then ... Feb 23 2006, 08:12 PM Egg Designer therefore Paul your answer is no, as the engines p... Feb 24 2006, 12:45 AM paul Hence my statement of ' My initial thought is ... Feb 24 2006, 07:46 AM Egg Designer ahh yes! will read closer next time, it was la... Feb 24 2006, 08:36 AM quaker no it wont take off , paul has it almost right ( ... Feb 24 2006, 09:19 AM james Yes it will :biggrin:
Think of it like this - h... Feb 24 2006, 10:14 AM paul No it wont now quiet the lot of you Feb 24 2006, 01:35 PM camsmith Why, did you put the parking brake on? :biggrin:
... Feb 24 2006, 01:55 PM jamie The plane aint going anywhere
(until you turn off... Feb 24 2006, 02:26 PM james Ok how about a different approach:
Imagine you co... Feb 24 2006, 02:31 PM
jamie
Ok how about a different approach:
Imagine you c... Feb 24 2006, 03:16 PM camsmith Alternatively, think about a matchbox car (I'm... Feb 24 2006, 02:37 PM james The planes lift is certainly not just being caused... Feb 24 2006, 02:40 PM womble I would agree with camsmith on this one. Planes do... Feb 24 2006, 02:50 PM Emily I am ment to know the answer to this question havi... Feb 24 2006, 03:16 PM camsmith
and i dont agree with the matchbox thing
the mat... Feb 24 2006, 03:26 PM Emily and the argument suggests that no matter how fast ... Feb 24 2006, 03:17 PM jamie James/ cam are you saying that at the exact point ... Feb 24 2006, 03:23 PM jamie which was my point. AIRSPEED, not converyer speed Feb 24 2006, 03:30 PM camsmith The running on a treadmill is again not a fair com... Feb 24 2006, 03:30 PM jamie If the planes 'speed' is being matched and... Feb 24 2006, 03:34 PM camsmith
If the planes 'speed' is being matched an... Feb 24 2006, 03:36 PM james Another version to help you visualise the solution... Feb 24 2006, 03:43 PM jamie I think you may need to read the first post again
... Feb 24 2006, 03:45 PM Emily can we leave out that plane taking off, we all kno... Feb 24 2006, 03:51 PM james J - you are not understanding the difference betwe... Feb 24 2006, 03:56 PM camsmith It's all about relative speeds...
A car's... Feb 24 2006, 03:58 PM james No worries hun (in case anyone wonders what we are... Feb 24 2006, 04:00 PM Emily we're about to have another now that you have ... Feb 24 2006, 04:02 PM Doctor My brain hurts :confused:
I took one look at th... Feb 24 2006, 04:06 PM camsmith I reckon we should use the treadmill, rollerblades... Feb 24 2006, 04:18 PM jamie I dont feel confused, I just think youre all wrong... Feb 24 2006, 05:13 PM paul A plane cannot take off without air moving over th... Feb 25 2006, 08:20 PM Emily will you all LISTEN and STOP talking about the blo... Feb 26 2006, 12:23 PM quaker computer says no Feb 27 2006, 01:09 PM Janette *cough* Feb 27 2006, 01:31 PM Egg Designer For the love of God! Cam - read the first pos... Feb 28 2006, 07:33 AM camsmith
For the love of God! Cam - read the first po... Feb 28 2006, 10:43 AM womble Ok this is a conversation I had from a colleague t... Feb 28 2006, 09:19 AM james Rory - I've run out of ways to explain how you... Feb 28 2006, 09:29 AM Emily can i ask the everyone read my post about the whee... Feb 28 2006, 09:36 AM womble Yeah id guess that close to how it works Em. As lo... Feb 28 2006, 09:44 AM james I don't understand that post Mike - on a freew... Feb 28 2006, 10:09 AM womble My answer was in 2 parts, one being with real phys... Feb 28 2006, 10:16 AM james Well yeah I understand what you are saying but as ... Feb 28 2006, 10:48 AM womble Yay you got it, its hypotheticaly what would need ... Feb 28 2006, 10:55 AM paul Anyone see the footie last night????? Feb 28 2006, 03:47 PM womble I bet all you saw was wedding books! :biggrin... Feb 28 2006, 04:57 PM quaker big stick immenent :ph34r: Feb 28 2006, 05:59 PM Egg Designer OK, I understand that forward thrust in the real w... Mar 1 2006, 08:37 AM james And therein lies the rub - nowhere in the question... Mar 1 2006, 10:39 AM |
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