50' chain of beads leaps and cavorts its way out of a jar

Steve Mould, Britain’s Brightest’s “science guy,” showed that if you put coil a 50’ chain of magnets in a jar and then casually toss out one end, the whole chain goes berzerk leaps and cavorts like an innocent colt on crystal meth, defying gravity and gravitas. In this video, Earth Unplugged gets Steve to explain…

This topic is for comments on the original blog entry at: http://boingboing.net/2013/06/27/50-chain-of-beads-leaps-and.html

These do not appear to be magnets. Looks more like the kind of beaded chain you’d find connected to a pen at the bank.


Sorry to keep pointing out errors in your posts today Cory - no offense intended.

Little wordfart here: “if you put coil”

And like Dean said - where are you getting the idea these are magnets?

Finally, I was hoping to see the io9 post that brought this to your attention, but that Via link only goes to the site’s front page. Here’s the actual link: http://io9.com/this-is-the-bead-chain-experiment-its-about-to-melt-y-602029455

Aha - now I see - io9 got it wrong about the magnets, too.

Right you are, Steve Mould hisself says “The chain is the stuff from vertical blinds. The thing you pull on to open and close them.” (see http://stevemould.com/siphoning-beads/)

Those chains are far more interesting than the magnetic beads anyway. I wish I had a big jar full of those…

Doing what Steve Mould suggests in his original article (search eBay for ‘metal 4.5mm bead chain’) reveals that you, too, can stop wishing and have your very own 50 m of beaded chain for the (not so) low low price of £1.95 per metre (or less; that’s the first hit). Big jar left as an exercise for the reader.

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So, no magnets, not a coil, and a colt who is doing meth is no longer innocent…


indeed. a magnetic chain coiled up like that would be stuck together and not have enough momentum to un-coil itself.

Just for what it’s worth: There have been versions of this with a looped chain and a motorized drive wheel. You don’t get the siphon effect, but you can perturb it and watch the standing waves.

Any chain or ribbon with a reasonable amount of momentum can be made to work, of course. I’ve seen an art-installation version that used a loop of fabric, with a drive mechanism that shoots the fabric upward quickly enough (and pulls the other side in quickly enough) to keep the whole thing floating in mid-air. The drive needs to be able to swivel to avoid tangling the loop, since it’s free to fall back to earth in any direction. The one I encountered was at MIT; it may have been done elsewhere and/or by other people.

Fun with Fizziks…

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So amazing. I think this is sort of like how a siphon works.

When he said he would hold it higher to get a bigger jumping loop I was expecting much higher. How about from the edge of a roof?

This looks like the Slinky effect.

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This needs to be done on a massive scale. With a really big ball chain and from a very great height. I would give a few dollars to a kickstarter for that.

An oil tanker’s anchor chain off the Burj Khalifa.

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One thing nobody seems to have mentioned yet is that these chains have a fairly large minimum bend radius, and a bit of springiness when that limit is reached.

Also, it’s fairly clear in the video that some of the kinks and swirls are actually ripples caused by the chain not being perfectly coiled in the jar.

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Glad to see I wasn’t the only one who thought that.

Why is this weird?

Don’t get me wrong - it looked weird to me at first. I watched the slo-mo and thought “It’s like it knows where the edge of the beaker is, and it’s avoiding it”. But I thought for a bit, and using the same arguments that the Science Guy did, reasoned that (a) the chain must be initially going up at pretty much the same rate as the bit outside is going down (b) it would need a pretty hard tug to get it moving that fast © the chain can only apply a force along its length, so it must move in an arc for the tension to change it from going up to going down without any other forces. Long story short: it would be surprising if it didn’t do something like this.

Think about gyroscopes. Common sense can be pretty rubbish at times.

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I once had a whole colander of spaghetti siphon itself out and onto the counter top. Just a bit hanging over the edge was enough to get it started. I guess it was sticking to itself a fair bit.

That is what I was thinking too, I suppose at some point you would get diminishing returns do to the weight of the chain in the loop.

Also how would the size and width of the jar mouth impact the motion?

Watching the slow motion portions of this was beautiful. It’s funny how slowing down video of almost anything makes it infinitely more pleasurable to watch. Why the hell is that?