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(Kottke)   Holy levitating Slinky   (kottke.org) divider line 24
    More: Spiffy, center of mass, scientific explanations  
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6521 clicks; posted to Video » on 21 Jun 2012 at 9:31 AM (2 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



24 Comments   (+0 »)
   
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2012-06-21 09:40:44 AM
Wow, that really farked with my head before coffee
 
2012-06-21 09:42:47 AM
that was weird... even when the top fell below the bottom the bottom stayed stationary until it was pulled down.
 
2012-06-21 09:46:06 AM
Slinkys is from the debil!

/cool vid
 
2012-06-21 10:19:59 AM
old-news-isn't-exciting.jpg

http://www.youtube.com/watch?v=O6RiPrk8dmE
Uploaded by 2 years ago by coderaptors on Dec 21, 2009
 
2012-06-21 10:22:25 AM
Reporter: "This looks much more realistic"
Researcher: "It is....that's why I did it...."
 
2012-06-21 10:46:42 AM

OnlyM3: old-news-isn't-exciting.jpg

http://www.youtube.com/watch?v=O6RiPrk8dmE
Uploaded by 2 years ago by coderaptors on Dec 21, 2009


Who cares? It's a cool video.
 
2012-06-21 11:34:00 AM

Wise_Guy: OnlyM3: old-news-isn't-exciting.jpg

http://www.youtube.com/watch?v=O6RiPrk8dmE
Uploaded by 2 years ago by coderaptors on Dec 21, 2009

Who cares? It's a cool video.


I was watching slinky videos before it was cool.
 
2012-06-21 11:45:05 AM

OnlyM3: old-news-isn't-exciting.jpg

http://www.youtube.com/watch?v=O6RiPrk8dmE
Uploaded by 2 years ago by coderaptors on Dec 21, 2009


For a brief moment this was a pretty nifty video until I realized it hadn't been filmed moments before I watched it let alone streamed live to my desk. I'm so farking over things I haven't seen before if they aren't current. It's why I don't watch movies if I can't watch the rushes daily. Some would say 'Hey dickface, not only are you a farking douche for being so pissy but you're also depriving yourself of seeing some classic movies by classic directors with classic actors by being such a hair splitting coont!' But to them I call BS, because there are people on fark who agree with me!!!!
 
2012-06-21 12:00:54 PM

OnlyM3: old-news-isn't-exciting.jpg

http://www.youtube.com/watch?v=O6RiPrk8dmE
Uploaded by 2 years ago by coderaptors on Dec 21, 2009


Your shiatty video is shiatty and somewhat unconvincing, unlike this one.
 
2012-06-21 02:24:41 PM
Description under the video is pretty good. The slinky isn't a rigid body and like with all things it is the center of mass that needs to primarily be considered when looking at gravitational attraction problems. The precise reason for why the bottom doesn't move until the center of mass reaches it is because when the slinky is just hanging before being released it is in equilibrium -- the spring force pulling upwards is exactly balancing the gravitational force pulling downwards and continues to do so once it is released. Could prove it mathematically, but it would involve lots of integrals and I'm way to lazy to do that right now.
 
2012-06-21 03:32:44 PM
The first song in the video sounds like the score to BBC One's Sherlock
 
2012-06-21 06:05:09 PM
It looks more like the bottom of the slinky doesn't know the top part is accelerating due to gravity. Why would it? It's reacting as if it's being held until the top finally pushes it towards gravity. I'm not a scientist but if it was pulling towards the center mass, the bottom would then move up, yes?
 
2012-06-21 07:07:20 PM
I wanna know how it is they never advertised this feature. Instead they used the incredibly lame "rolls down stairs" trick which I think was just made to frustrate a generation of children.
 
2012-06-21 07:16:21 PM
As a girl, I wish to say that this was fun, and I believe it also would be for a boy.
 
2012-06-21 09:07:59 PM

StrangeQ: Description under the video is pretty good. The slinky isn't a rigid body and like with all things it is the center of mass that needs to primarily be considered when looking at gravitational attraction problems. The precise reason for why the bottom doesn't move until the center of mass reaches it is because when the slinky is just hanging before being released it is in equilibrium -- the spring force pulling upwards is exactly balancing the gravitational force pulling downwards and continues to do so once it is released. Could prove it mathematically, but it would involve lots of integrals and I'm way to lazy to do that right now.


Does it have to be a spring? If you dropped a long rope (or your mom, if we're talking about heavy, loose objects) would it also levitate?
 
2012-06-21 09:25:57 PM
AverageAmericanGuy: Does it have to be a spring? If you dropped a long rope (or your mom, if we're talking about heavy, loose objects) would it also levitate?

Yes, but the effect would not be nearly as obvious, because the levitation would last a much shorter length of time. The slinky is under tension when it is stretched because it wants to return to the more compact shape, and the act of dropping it releases the tension at the top, but the bottom is still being pulled up by the tension in the middle and that is what makes it looks like it is levitating. A rope would not have the same tension to return to a smaller form, so the delay would simply be the time it takes for lack of upward force holding the rope from dropping to propagate down through the rope.
 
2012-06-21 10:00:47 PM

Slives: Yes, but the effect would not be nearly as obvious, because the levitation would last a much shorter length of time. The slinky is under tension when it is stretched because it wants to return to the more compact shape, and the act of dropping it releases the tension at the top, but the bottom is still being pulled up by the tension in the middle and that is what makes it looks like it is levitating. A rope would not have the same tension to return to a smaller form, so the delay would simply be the time it takes for lack of upward force holding the rope from dropping to propagate down through the rope.


api.ning.com
 
2012-06-22 08:38:33 AM

OnlyM3: Uploaded by 2 years ago by coderaptors on Dec 21, 2009


Thank you good sir for policing reposts!

And to think I was enjoying it as I didn't see it before. Let me warm myself in the glow of your superiority.
 
2012-06-22 01:40:54 PM

StrangeQ: Description under the video is pretty good. The slinky isn't a rigid body and like with all things it is the center of mass that needs to primarily be considered when looking at gravitational attraction problems. The precise reason for why the bottom doesn't move until the center of mass reaches it is because when the slinky is just hanging before being released it is in equilibrium -- the spring force pulling upwards is exactly balancing the gravitational force pulling downwards and continues to do so once it is released. Could prove it mathematically, but it would involve lots of integrals and I'm way to lazy to do that right now.


It's actually simpler than that.

The spring's tension is exerting an upward force, gravity is exerting a downward force. At the start, when the slinky is still held, the top is in place due to being gripped, and the bottom is in place as it's at the balance point between the spring's upward tension and the downward pull of gravity. When you release the top, it has both the downward pull of gravity AND the downward pull of spring tension (which pulls towards the "middle" which is an oversimplification at any point but either end), while the bottom is still experience the same upward spring tension and downward gravity as before.

It's only when the spring section above the bottom collapses, changing the spring's tension force on the bottom, that the dynamic at the bottom is upset.

You don't need the math really, since it's starting from a place of balance; the spring has extended down until the upward tension is the same as the downward force of gravity.
 
2012-06-23 07:25:54 AM

rudemix: OnlyM3: old-news-isn't-exciting.jpg

http://www.youtube.com/watch?v=O6RiPrk8dmE
Uploaded by 2 years ago by coderaptors on Dec 21, 2009

For a brief moment this was a pretty nifty video until I realized it hadn't been filmed moments before I watched it let alone streamed live to my desk. I'm so farking over things I haven't seen before if they aren't current. It's why I don't watch movies if I can't watch the rushes daily. Some would say 'Hey dickface, not only are you a farking douche for being so pissy but you're also depriving yourself of seeing some classic movies by classic directors with classic actors by being such a hair splitting coont!' But to them I call BS, because there are people on fark who agree with me!!!!


yeah? well my dad said that his highschool physics teacher used this demonstration to 'wow' kids back when he was a hipster in ninteencanteen, and his onions were belted when everyone was still wearing chives on their pantaloon-bracing apparatus.
 
2012-06-23 12:39:37 PM
Meh. I figured this out without reading the explanation, and I was an English major.
 
2012-06-24 12:48:43 AM
You have just invented the clock!
 
2012-06-24 12:52:20 AM
 
2012-06-24 09:40:46 PM

Sylvia_Bandersnatch: As a girl, I wish to say that this was fun, and I believe it also would be for a boy.


WIN!
 
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