Wraith2 (stardust savant)
06/22/06 06:31 PM
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A Physics Riddle
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If an airplane is on a large conveyor belt and is trying to take off by exerting the thrust needed to move it forward at 100 knots, and the conveyor belt starts moving backwards at 100 knots, will the plane be able to take off, or will it just sit stationary relative to the ground, with the backwards speed of the conveyor belt counteracting the forward thrust of the plane?
Explain your answer.
Emil, I expect you to get this.
I just want to hold your pretty hand; the rest of you can be dissolved in acid
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anisette (acolyte)
06/22/06 07:08 PM
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Wait, I know this.
It's a trick question because you don't *bury* survivors.
Betcha didn't expect me to get this. 
"And generally speaking, I’m not a guy who is well-disposed towards mullets." -- D. F.
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to_dizzy (crash course raver)
06/22/06 07:56 PM
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NO, that's wrong, You do bury survivors, unless the entire boat was torpedoed.
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Wraith2 (stardust savant)
06/22/06 08:20 PM
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What if it's a heat seeking torpedo?
In reply to:
Ani: Betcha didn't expect me to get this.
Hey, mang, it ain't atomic science. Besides, you were a statistics major. Or was that someone else? 
I just want to hold your pretty hand; the rest of you can be dissolved in acid
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Monkeyboy (band intro)
06/22/06 08:52 PM
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Answer: All things are possible through Christ.
(insert catch phrase)
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GreatApe (kook)
06/22/06 10:39 PM
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the plane will stay still relative to the ground. it won't take off because the Earth is the air's inertial frame (more or less) and the two speeds add up to 0, therefor the plane is just fighting to stay still.
now.... "knot (kn or kt) [1] a unit of velocity equal to one nautical mile per hour. Knots are customarily used to express speeds at sea, including the speed of the ship as well as the speeds of the wind and of the current. The word comes from the former method of measuring a ship's speed, which involved use of a knotted cord called the log line. One knot equals about 1.1508 miles per hour, exactly 1.852 kilometers per hour, or 0.5143 meters per second. Since kt is the established symbol for the kilotonne, kn is the best choice as a symbol for the knot. knot [2] an informal unit of distance equal to the nautical mile."
you chose an odd unit of measure, Wraith. But it still works.
And what costumes shall the poor girl wear to all tomorrow's parties? Thursday's.... fucking SHIT! - All Tomorrow's Parties Demo, Take 1
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Atonalexpress (acolyte)
06/23/06 00:51 AM
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the plane will not take off because you need air speed and this plane ain't got none.
Ampersand
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tofuescape (grinning soul)
06/23/06 05:01 AM
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Thats like: If you are on sailing boat on a still day and you attach a big fan to the deck and point it at (red) the sails, will the boat move?
I like holding stuff.
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sonofsilence (two inch thoughts)
06/23/06 05:15 AM
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that's Like saying if Bowie had a website and charged everyone to become a member would they pay up?
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anisette (acolyte)
06/23/06 05:18 AM
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In reply to:
Hey, mang, it ain't atomic science. Besides, you were a statistics major. Or was that someone else?
um...if you're talking to me (mang?), uh, I was a theater major. I got my degree in make-believe, ok?
Maybe you're thinkin of dice, he's the guy with the stats.
"And generally speaking, I’m not a guy who is well-disposed towards mullets." -- D. F.
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Strawman (acolyte)
06/23/06 05:43 AM
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Exactly how long is the conveyor belt?
COME ON ENGLAND!
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sonofsilence (two inch thoughts)
06/23/06 05:49 AM
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and what colour is it?
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Strawman (acolyte)
06/23/06 06:04 AM
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Brian, I'd kindly advise you not to take the piss, my question is a relevant one.
For instance, if the conveyor belt is sufficiently long that plane is taking off. It doesn't matter what the conveyor belt is doing because the airplane's energy is acting on the air, not the belt - I shall simplify the problem thusly: imagine instead of a plane, you've got a rocket with wheels sitting on that belt - when that rocket fires, it's eventually going to rocket off the end of that belt, which means that it doesn't remain stationary to the ground, and if it had wings, it would fly.
COME ON ENGLAND!
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exorcist (grinning soul)
06/23/06 06:19 AM
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THE POWER OF CHRIST COMPELS A PLANE TO GET ITS LIFT VIA THE BERNOULLI EFFECT! THIS HAS TO DO WITH WING SHAPE AND ITS INTERACTION WITH AIR MOVING RAPIDLY PAST! IF THE PLANE HAS NO MOTION RELATIVE TO THE WIND, THERE WILL BE NO LIFT TO FORCE THE FUCKING PLANE UP!!
THAT PLANE IS GOING NO WHERE FAST!! KIND OF!
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Nature_Boy (crash course raver)
06/23/06 07:31 AM
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The exorcist's word of Christ speaks the truth:
an aeroplane's wing is shaped so that when moving forward, the air moving under the wing is moving faster than the air on top of the wing. This creates a pressue gradient and thus an upwards force (commonly called "thrust", or "upthrust").
If you are on a conveyor belt no air is moving past the wing, hence no upwards thrust.
Its about time I had a signature
The Thin White Duke: David Bowie Tribute Band
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Dara (acolyte)
06/23/06 08:56 AM
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The wheels of a plane are not there to make it move: they're not motorized. They're there to reduce friction during takeoff and add friction when landing. What moves a plane forward are jet turbines or propellors which move the air backwards, thereby propelling the plane forward.
So the plane will move forward relative to the ground at the same speed as normal (100 knots), and will be moving forward 200 knots relative to the conveyor belt. So the wheels of the plane will be moving at twice their normal speed, and the plane will take off.
Slan libh,
Daz
"I could count my friends on one hand, but I'd look like I was giving an invisible friend a hand job." - Shelle
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Asteroid (kook)
06/23/06 09:09 AM
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Hello are you a pilot? That plane isn't gonna lift off unless it has a very unusual aspect ratio (wing shape) and an unusually large prop.
The prop produces thrust which helps drag the plane through the air. That air, flowing over the wings, produces lift. The prop is not simply a fan that blows air over the wings.
Don't act like you're above somebody if they insult you. Stop implying that monkeys only eat bananas - by Schizophrenic
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sonofsilence (two inch thoughts)
06/23/06 09:13 AM
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what if there are ridges on the converor belt creating wind current?
and it is a windy day?
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diamondogz74 (freecloud)
06/23/06 09:22 AM
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In reply to:
The wheels of a plane are not there to make it move: they're not motorized
I might be missing something here, but how does an airplane taxi?
London Bye Ta-Ta...
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Dara (acolyte)
06/23/06 09:38 AM
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This page explains it a bit better than I attempted to.
Slan libh,
Dara
"I could count my friends on one hand, but I'd look like I was giving an invisible friend a hand job." - Shelle
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Nature_Boy (crash course raver)
06/23/06 10:43 AM
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I think i'm gonna bail out of this discussion, just the very though of planes is making me queezy. I have to be tanked up on valium before I can even step foot in one.
Its about time I had a signature
The Thin White Duke: David Bowie Tribute Band
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Wraith2 (stardust savant)
06/23/06 11:22 AM
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In reply to:
Ani: Maybe you're thinkin of dice
Honestly, I'm always thinkin' of dice.
In reply to:
Strawy: Exactly how long is the conveyor belt?
Infinite length.
In reply to:
Sonny: and what colour is it?
Off chartreuse. How windy it is doesn't matter.
I just want to hold your pretty hand; the rest of you can be dissolved in acid
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sonofsilence (two inch thoughts)
06/23/06 11:24 AM
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In reply to:
Off chartreuse
ok. that changes everything.
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Strawman (acolyte)
06/23/06 11:25 AM
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In reply to:
Off chartreuse.
I figured that much.
COME ON ENGLAND!
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dice (every nation's refugee)
06/23/06 12:57 PM
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my guess upon looking at the initial question would be that the plane lifts off vertically like a helicopter before thrusting forward (no whiplash for passengers)
In reply to:
Infinite length.
cool! you could land on the conveyer belt above the clouds without slowing down! then people could climb out on the stationary wings and dance!
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Atonalexpress (acolyte)
06/23/06 02:22 PM
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i'd like to know how wide the conveyor belt is.
Ampersand
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CharlieManson (kook)
06/23/06 02:32 PM
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What the fuck is a plane doing on a fucking conveyor belt?
I'll slash them cold, I'll kill them dead I'll break them gooks, I'll crack their heads I'll slice them till they're running red But now I've got the running gun blues
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Strawman (acolyte)
06/23/06 02:46 PM
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COME ON ENGLAND!
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Starlite (acolyte)
06/23/06 04:06 PM
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I can't believe you didn't respond to my tomato.
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forgetthatim50 (kook)
06/24/06 04:28 PM
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not doodly to do with this but it is physics so pretence enough ;a nagasaki site says the energy in ilb of tnt will take 36 gallons of water from freezing to boiling,1lb of uranium will do the same to 200million gallons. article also said hiroshima bomb up rooted trees,nagasaki bomb snapped them off at their base.
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th0mas (acolyte)
06/24/06 09:57 PM
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Hmm, but wouldn't the runway be half as long?
 Liest das denn keiner außer mir?
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anisette (acolyte)
06/25/06 09:34 AM
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And I can't believe you didn't caress his cucumber.
"And generally speaking, I’m not a guy who is well-disposed towards mullets." -- D. F.
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Emil (acolyte)
06/27/06 07:29 AM
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Sorry, I've been celebrating midsummer so I missed out on this one. 
What I really want to know is, what happens when you put a bag on a conveyor belt -- under what conditions can it gain enough airspeed to take off and fly in a direction opposite to the one that its owner had intended, finally ending up on Reykjavik airport?
Laa.
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diamondogz74 (freecloud)
06/27/06 10:17 AM
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In reply to:
What I really want to know is, what happens when you put a bag on a conveyor belt
Ask her...

London Bye Ta-Ta...
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Emil (acolyte)
06/27/06 10:20 AM
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??
Please explain.
Laa.
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diamondogz74 (freecloud)
06/27/06 10:24 AM
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In the UK and maybe in america, I'm not sure? we sometimes call women who have caused trouble or are a nuisance, an old bag.
London Bye Ta-Ta...
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