The Sphere
General Garbage => Tropical Paradise of Hard Shelled Fruits => Topic started by: The D on Feb 23, 2006, 04:55:25 PM
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This has stumped people on other boards and even started an argument on 4chan's IRC channel.
Imagine a jet plane (although it could probably be any sort of plane), and a runway that's a giant treadmill. When the plane's on the treadmill, the treadmill matches the plane's airspeed (relative to the ground) but in the opposite direction. So when the plane's at the end of the runway/treadmill going 0mph, the treadmill's going 0mph. When the plane's traveling at 80 knots facing north, the treadmill's going 80 knots southward.
Does the plane take off? This answer doesn't require complex math, just common sense.
I believe it can take off. I'll say why after a while, to see if someone else can explain it.
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If there's opposing motion, there's no drag.
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Wrong.
And no mention of planes is complete without this:
(http://pics.livejournal.com/tongodeon/pic/0000c20d/s640x480.jpg)
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Wrong.
No, not wrong. If the plane is stationary, there is nothing moving through the air, which means there's no drag, which means the plane couldn't make lift.
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He's right. As much as I hate to admit it. If the plane isn't moving forward, Lift can't build up under the wing and therefore it can't rise off the ground. The way a plane wing works, is that the bottom is flat and the top is curved. When it cuts though the air, it takes longer for the air to travel over the wing then he does under the wing and this causes lift. If there is no forward movement, then this won't happen.The people at those other boards are just dumb.
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The plane should just try vomiting for a few weeks. Then it'll fit into that prom dress, no problem.
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He's right. As much as I hate to admit it. If the plane isn't moving forward, Lift can't build up under the wing and therefore it can't rise off the ground. The way a plane wing works, is that the bottom is flat and the top is curved. When it cuts though the air, it takes longer for the air to travel over the wing then he does under the wing and this causes lift. If there is no forward movement, then this won't happen.The people at those other boards are just dumb.
Aren't you glad I wasn't aborted?
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Yeah. Plane won't take off. This is my opinion as an engineer and, briefly, air cadet as well as non idiot.
The reason is stated above. Plane uses it's movement relative to the air around it, not the ground, to take off.
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I hate 4Chan...so very much...
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He's right. As much as I hate to admit it. If the plane isn't moving forward, Lift can't build up under the wing and therefore it can't rise off the ground. The way a plane wing works, is that the bottom is flat and the top is curved. When it cuts though the air, it takes longer for the air to travel over the wing then he does under the wing and this causes lift. If there is no forward movement, then this won't happen.The people at those other boards are just dumb.
Aren't you glad I wasn't aborted?
Eh....I could go either way.
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Eh....I could go either way.
I LOL'D.
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I just want someone to love me!
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I could go either way.
I just want someone to love me!
...are you hitting on me? :huh:
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I hate 4Chan...so very much...
4chan loves me
(http://img.photobucket.com/albums/v720/IDE/theylikeit.jpg)
(http://img.photobucket.com/albums/v720/IDE/1114922398600.jpg)
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Rama almost answered correctly, but he didn't.
Now,here's the real answer. And it's real cause my dad being a pilot, I probably know more about airplanes than most of you B)
Wait, oh shit I was gonna talk about the big airplanes, i don't know about little jets. forget it.
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Damn you Faye, getting my hopes up like that.
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Rama almost answered correctly, but he didn't.
Now,here's the real answer. And it's real cause my dad being a pilot, I probably know more about airplanes than most of you B)
Wait, oh shit I was gonna talk about the big airplanes, i don't know about little jets. forget it.
The basic princple is the same for all winged aircraft. Large or small...The only difference is the amount of powet it takes to reach lift off speed. IE: the larger the plane the more powet you need.
Now if you had an Anti-gravity driven aircraft then that's different...but those arn't suppose to exist. :unsure:
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How did Faye give us an answer when she didn't..?
WORST EPISODE EVER!
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You can have a nuclear-powered rocket engine with the ability to reverse the Earth's rotation, and it wouldn't matter. If there's an equal and opposite force holding the plane in it's fixed position (the treadmill matching velocity), there is no relative airspeed; i.e., no air is passing under the wing and thus no lift.
Saying it can is idiotic.
(http://virtualskies.arc.nasa.gov/aeronautics/tutorial/images/AirPressure.gif)
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*already said that* <.<
Why does anyone go to 4chan aside for looking for pr0n?
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"6 Firefox"? FTW? Are you telling me you're not using the tabs and actually have six windows open? Why?
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*already said that* <.<
Why does anyone go to 4chan aside for looking for pr0n?
There's this guy that posts there that's really funny.
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...and incidentally has manga-boobies.
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oh you know anonymous.
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You're wrong, and you make the assumption that everyone makes, which is incorrect.
First off, you're comparing your thinking to that of a car on a treadmill. Since the car propells itself forward by friction from the ground, if it's driving on a treadmill going the same speed, the speed of the treadmill cancels out the speed of the car.
However, an airplane has wheels that freely turn. And the plane gets it's thrust from the engines, not the wheels. As the plane starts to accelerate from zero, the conveyor belt would match it's speed. The wheels would spin along with the belt, but the plane itself would be mostly unaffected by the backwards movement of the treadmill. Thus, the plane WOULD be moving forward and would have air traveling under the wings and would take off.
I have websites to prove it, too!
http://experts.about.com/q/Physics-1358/Ai...ving-runway.htm (http://experts.about.com/q/Physics-1358/Airplane-moving-runway.htm)
http://www.straightdope.com/columns/060203.html (http://www.straightdope.com/columns/060203.html)
Also, you guys failed to take into account the plane might be a VTOL or be flying into a really STRONG wind.
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And the wind is blowing in the exact direction of the airplane, and I mean exact without crosswinds?
And most of the stuff found online is crap, and this smells of it. Even with the engines providing the movement, the plane is still remanining stationary.
If this was a viable option, we wouldn't still build aircraft carriers.
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VTOL
A VTOL doesn't have to use a runway to take off. Why would it even have wheels? By your analogy the treadmill would be completely immobile.
As for the other stuff... it's crap. If like "you" say the plane is moving faster than it's wheels then it's already flying and it can't get to that speed to fly just a little if it's not actually moving relative to it's outside environment because of the conveyor belt. What you're saying is like... if you tied a plane up and put it on blocks and then cut the cord as you removed the blocks then the plane would just start from a stationary position.. well yeah I don't believe that. The plane would go down, at least a bit, before getting speed and raising itself and unless the initial momentem takes it go up right off before going forward then the treadmill thing is crap.
As for wind it would have to be so strong that it would make an immobile plane just take off... which is retarded. Planes parked on a runway don't generally just take off when it's a bit windy.
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Mind did, but then again it was made out of paper.
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I'm still right, fools! (http://www.avweb.com/news/columns/191034-1.html)
It was an interesting argument, but as things progressed, more rational heads prevailed, pointing out that the airplanes do not apply their thrust via their wheels, so the conveyor belt is irrelevant to whether the airplane will takeoff. One guy even got one of those rubber band powered wood and plastic airplane that sell for about a buck, put it on the treadmill someone foolishly donated to the Lounge years ago, thinking that pilots might actually exercise. He wound up the rubber band, set the treadmill to be level, and at its highest speed. Then he simultaneously set the airplane on the treadmill and let the prop start to turn. It took off without moving the slightest bit backwards.
They even did the experiment and it worked!
I also like the comparison to the hovercraft. Stick a hovercraft on this conveyor belt runway, and no matter how fast the conveyor belt rotates, the hovercraft will still travel forward... there's little friction with the ground.
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Who the fuck is Rick Durden, and if he was so smart, why does he blog instead of fuck supermodels in the Turks and Caicos Islands like Bill Gates, Lockheed and Martin.
You fail, and so does Rick Durden.
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No. That's crap. The reason for which the planes actually took off is because the treadmill was unable to keep up with the speed of the plane. The way these people seem to think the plan would take off is that the powet of the turbines pushing the plane would make it just fly forward and not stick to the treadmill. But the problem is you can't perfectly duplicate such a treadmill. If the plane is allowed to lose it's grip on the tread and move forward before going upwards, wich is the only way in which a plane can fly because upwards motion is only caused by the wind under the wings caused by the forward motion, then the speed of the plan is not all being compensated by the treadmill. It's just not able to keep up.
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I think you are wasting your time. D would tell the Wright Brothers they where wrong, and would be completely serious about it.
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First off, you're an idiot if you can't understand why it can't happen.
To reiterate, air has to move around the wings in order to create lift. And ths air must move at a speed that produces enough lift to actually pull the plane upwards. If the plane is accelerating forward while the ground is moving backwards, the plane is not moving and air will not move around the wings at a sufficient speed to generate the sufficient lift required to pick it up off the ground.
I don't give a crap where the thrust comes from. The fact is that it IS NOT MOVING, and thus there is not enough airflow to produce lift. And it doesn't matter if the wind is blowing, or how hard, because unless it's a fucking hurricane or tornado, it's not going to be strong enough to blow over the wings and lift it.
I work in a place that tests jet engines on a daily basis. If you strap a jet down and burn the engines, guess what? It doesn't lift. Same thing here, except instead of straps you have a treadmill keeping the thing stationary.
Now pull your head out of your ass and find something else to go on about.
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EVERYBODY CHILLLLL OUTTT!!!
I'm gonna be running on a treadmill later tonight. I'll flap my arms when no one is looking and we'll settle this once and for all!
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Bring souvenirs.
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EVERYBODY CHILLLLL OUTTT!!!
I'm gonna be running on a treadmill later tonight. I'll flap my arms when no one is looking and we'll settle this once and for all!
I'm not convinced you couldn't do so from a stationary position making you a human equivalent of a VTOL craft.
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I give up on you guys, you aren't reading the articles properly, you're not thinking properly. For one thing, the plane is not STICKING to the treadmill, it's resting on the treadmill on the wheels, which roll freely. The thrust is from the engines. The engines push it forward, the wheels spin backwards freely with the treadmill and don't impede on the plane's movement, and the plane's thrusted forward, air goes under the wings, and it takes off.
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I flapped as hard as I could and nothing happened.
Case Closed.
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is there someone here who actually cares about how planes fly? damnit i've heard about planes for my whole life.
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I flapped as hard as I could and nothing happened.
Case Closed.
ONE TRUTH PREVAILS!
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I give up on you guys, you aren't reading the articles properly, you're not thinking properly. For one thing, the plane is not STICKING to the treadmill, it's resting on the treadmill on the wheels, which roll freely. The thrust is from the engines. The engines push it forward, the wheels spin backwards freely with the treadmill and don't impede on the plane's movement, and the plane's thrusted forward, air goes under the wings, and it takes off.
You know WHY people use treadmills? Because they can WALK all day yet not GO anywhere. The same with a plane.
The engines do not propel the plane upwards, only forward. It's like a car on a dynometer...you can measure the powet output of the car at the rear wheels, but it's not "making wind" around it. If the plane is not "making wind" around it, there'll be no lift.
You could have Jesus AND Chuck Norris pushing it from behind, but if the treadmill can match that speed in the opposite direction, it's not going forward.
I'm not conceding this.
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Jesus and Chuck Norris together? I'd pay to see that.
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He's Jesus, lol.
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As much as I am loathe to admit it, D's right on this one. It would take minimal additional thrust from the engines to overcome the opposing motion of the treadmill, mostly due to the effects of lost energy due to friction in the wheel bearings. When you stop to consider the fact that the wheels on the plane are essentially there to keep it from having to slide around on it's belly, the answer becomes rather obvious.
Let's put it this way:
Remove the wheels completely and allow the plane to be suspended by, I don't know, some anti grav unit that's only strong enough to lift it a few feet off the ground. The jet turbines engage and the air is compressed, fuel added and combusted,, then allowed to expand again, providing thrust (if you want I could go into the specifics of the Brayton cycle, but I doubt anyone's interested). All of this happens completely independent of any interaction with the ground. The ground could be screaming backwards at 2x the speed of sound and it wouldn't bother the jet. We're not worried about lift here, we're just talking about simple horizontal locomotion. (the lift comes as a result, but it's rather inconsequential to the heart of the problem)
Let's put the wheels back. Now the wheels, of course, are not the ideal suspension device the theoretical anti-grav unit is. There are inherrent innefficiencies, including the aformentioned friction. This would, indeed, cause some small amount of backwards force. But the magnitude of that force and the resulting motion is negligable compared to the thrust that the turbines can put out.
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Jesus and Chuck Norris together? I'd pay to see that.
I'm picturing Jesus clinging onto Chuck Norris' back, his fingers gripping the abundant amount of hair, and recoiling in horror as he realizes he's sinking.
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I was kinda hoping for "Sidekicks 2."
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Sam makes sense and I concende that his explanation makes me thing this would work. This isn't really in fitting with how the question was asked though as it seems that for every forward thrust there is a backward thrust on the plane stopping it in the same way by this threadmill. Like if the wheels were perfectlyfrictionless at the joints. I guess what's causing that way to make sense is the friction at the wheel's joint (whatever that's called) as well as a lack of proper adhession between the wheels and the treadmill.
None of these sites, and especially not the guy who's trying to explain it who doesn't understand it..., have made it make sense like he did.
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well, he IS an engineer.
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It's kinda an ideal explanation, so to me I don't see it working. If it was possible, the miliary would be using it.
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Yeah they wouldn't need to be investing millions into a VOTL NATO fighter if this actually worked. Besides you have to throw so many rules out the window to make it work and the question didn't really address that very well. It’d be like saying imagine you have a sub under water, but the rules of hydro dynamics don't apply.... Then really what's the point of it being underwater?
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Yeah they wouldn't need to be investing millions into a VOTL NATO fighter if this actually worked. Besides you have to throw so many rules out the window to make it work and the question didn't really address that very well. It’d be like saying imagine you have a sub under water, but the rules of hydro dynamics don't apply.... Then really what's the point of it being underwater?
If this "worked" it still wouldn't provide any useful advantage. You'd just be wasting energy running a treadmill and getting nothing but some waste heat generated by the friction in the bearings.
But the whole point is the treadmill wouldn't be useful at all; it's not like it allows the jet to build up a lot of thrust without moving forward. The jet moves forward and takes off as if nothing is going on underneath it.
As a fun little aside, the jet *would* get an insignificant boost forward if it was still on the ground when it got to the edge of the treadmill since the wheels would be rotating faster than the jet is moving forward. That tiny amount of kinetic energy (1/2*I*w^2, where I is the moment of inertia of the wheel and w is the angular velocity [in rad/sec]) would be transferred to the plane (1/2*m*v^2, where m is the mass of the plane and v is the linear velocity). Since the plane is so much more massive (m) than the wheel (I, which is directly related to the mass of the wheel and it's shape), the velocity increase is negligable.
But it's still there.
I hope you all took notes, there'll be an exam on Friday.
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Fuck this shit, I am a history student. Unless the production of this affects society, and it's use helps turn the tide of war or oppresses women, then maybe, otherwise fuck a 4chan for wasting my time over a useless and improbable innovation that has in no way aided soceity, and proved to do nothing more than bog it down. Shit, this needs more anime pr0n.
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that being said, I almost wanted to argue the opposite side, since the attitude of the question and D's replies struck me as having a "Ha ha, I'm smarter than you" tone
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Just smile at the anime pr0n.
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(I'm not smiling at the anime pr0n of the girls that look like they're 12, tops)
It also may help to look at the wheels in the extreme situations.
First, let's imagine the wheels as having an efficiency of zero. They're completely rusted in place, essentially no better than a concrete block strapped onto the belly of the plane. In this case the plane would move backwards as soon as the treadmill starts moving.
(translational --> 100% translational)
Next, imagine the wheel is an ideal component -- no friction in the bearings. Any kinetic energy transferred to the wheel by the treadmill at the contact surface is converted completely into rotational energy. The plane stands in one place and the wheels spin at a rate determined by the treadmill speed.
(translational --> 100% rotational)
Reality lies somewhere between.
(translational --> X% translational + Y% rotational)
...damn I'm a nerd. This is actually interesting to me.
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What anime chick looks of age? They're Japanese!
Plus, they have boobs.
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I thought that the idea was to make them look 12....It's like what they are "into" over there. You get none of the guilt cause they arn't real. Clever loophole you cheeky bastards.
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lolilicious!
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LOLIGASM!
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I thought that kind of pics were prohibited in this board
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There's no nudity.
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I see a nipple!!
Nuri, I think the best for us all is if you ban tom. he's corrupting our little society with disgusting and obscene pictures of naked cartoons!
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*cough*
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What kind of a world do we live in where Tom can't post some toon nipple, but IDE can post a pic of himself naked except a small stuff animal covering his boys. I don't want to live in a world like that!!!!
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You don't have to get all uppity. I'll post a pic without the stuffed animal.
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AAAAAAAAAAAAAAARRRRRRRRRRRRGHHH!!!!!!!!
:: stabs out his own eyes with a spork. ::
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Can I borrow your spork?
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Now that you guys aren't using your sockets anymore would you mind if...ahh you probably would.
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...Faye does that.
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What kind of a world do we live in where Tom can't post some toon nipple, but IDE can post a pic of himself naked except a small stuff animal covering his boys. I don't want to live in a world like that!!!!
Ok , are you BLIND? last time i looked, Nuri was the owner of the board! she being a woman would be ok with guys showing their ""assets", especially if they are nice(cause we don't wanna see a tom naked here)
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...you don't?
I'm fucking hot naked.
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well, he IS an engineer.
Me and Scott, who were both arguing the opposite, are also engineers.
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But I don't have this image of Shelly, which undermines you credibility.
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That's not me. That's my friend Ali.
This is me:
(http://adamrulz.com/digicam/thanksgiving/images/tg2004_21.jpg)
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Well, I guess you told me.
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SPONGEBOB!! how did you dare!
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(http://adamrulz.com/digicam/thanksgiving/images/tg2004_21.jpg)
A man humping a giant sponge.... This image is one line about the dangers of teen pregnancy away from a contraceptive ad.
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I LOL'D
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Kary laments at Sponge's lost anal cherry, or whatever the fuck sponges have.
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(http://adamrulz.com/digicam/thanksgiving/images/tg2004_21.jpg)
A man humping a giant sponge.... This image is one line about the dangers of teen pregnancy away from a contraceptive ad.
DUDE, that is a contraceptive.
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haha I still remember Seinfeld's episode about it.
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With all due respect, it still doesn't matter. Under the assumptions presented with this question, the treadmill matches the plane's speed...no matter the change in acceleration, the speed would still be matched. What loss can be accounted for by the wheel bearings/suspension/friction/etc. is inconsequential because the situation is essentially one where friction can never be overcome to produce forward motion. So the engine can provide a constant, increasing, decreasing, or non-existant acceleration, but the speed would continue to be matched.
well, he IS an engineer.
Me and Scott, who were both arguing the opposite, are also engineers.
I personally found physics I to be one of the more fun classes in our curricula.
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Hey man.....we are talking about the Sponge now. Get with the times.
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(http://adamrulz.com/digicam/thanksgiving/images/tg2004_21.jpg)
A man humping a giant sponge.... This image is one line about the dangers of teen pregnancy away from a contraceptive ad.
DUDE, that is a contraceptive.
That was kinda the joke.
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Your mom's a joke...
That's why people laugh, if you didn't know.
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Am I the only one who thought it was a waste to not have someone else on the other end of the sponge? I mean, he does have a mouth.
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RIDE THE SPONGEBOB TRAIN!
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Am I the only one who thought it was a waste to not have someone else on the other end of the sponge? I mean, he does have a mouth.
If I had a clone I'd be all over that but it's not so easy to find someone to go along with my shenanigans most of the time.
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You could always photoshop yourself in... Think the same camera tricks they used to film "The Parent Trap" only your twin is helping you double-team Spongebob!
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....when he's not getting giant implants or being a whore!
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A photoshop with 2 of me?
Like this:
(http://adamrulz.com/images/temp/clonish.jpg)
Wasn't actually done with photoshop though so technically that term does not apply.
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HAWT!
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LOLIGASM!
Tom's into that gay beachboy sex.
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Who isn't?
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A photoshop with 2 of me?
Like this:
(http://adamrulz.com/images/temp/clonish.jpg)
Wasn't actually done with photoshop though so technically that term does not apply.
I loled.
Who isn't?
The Academy of Motion Pictures
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I loled.
Funny how doug now is imitating the way of speaking of IDE. Watch out son!
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Your mom's a joke...
That's why people laugh, if you didn't know.
Hey....I'm not going to disagree with you.