Talk:Chain fountain

Prehistory

In Spivak's Physics for Mathematicians: Mechanics I (2010), Addendum 3A, especially pp 105-107, this phenomena is discussed (at least insofar as the downward force is greater than 1G; the "siphon" effect is left implicit), and he actually cites a paper noting this effect by Calkin & March from 1989. 166.137.242.45 (talk) 05:26, 25 October 2014 (UTC)

Hanging chain. It is predicted by energy conservation that if the right end is released, it will accelerate downwards faster than g.

Thanks for the comment, this is interesting reading as well. For the link-inclined, there is this arXiv by Wong and Yasui. They reference doi:10.1119/1.16114 which is probably the Calkin & March that you are referring to, unfortunately not open access but the gist seems to be described in the arXiv paper. The situation described is that of a hanging chain supported on both ends so that it forms a tight U shape (the ends held close together). The counterintuitive effect is that when one end is released, it accelerates to the ground faster than our familiar 9.8 m/s^2. So they do not describe an upward siphoning effect but instead there is a super-gravitational acceleration downwards. Of course this is related to the tension that overcomes gravity in the self siphoning beads.

As described in the arXiv paper, the phenomenon is related to the crack of a whip and results from energy conservation and concentration into the falling length of chain. A nice physics lesson for sure and I think worth mentioning in this article. --Nanite (talk) 13:18, 25 October 2014 (UTC)

Interesting. Re: whips, Spivak's addendum is actually titled Whips & Chains. Re: the upwards "siphoning" effect, isn't that directly related to the downwards motion (whether >1G or not)? The part of the chain still in the cup will need to be pulled up and out of the cup, so it will have an upwards momentum, which cannot be immediately reversed once it leaves the cup; again the whip analogy is probably the most intuitive way to visualize it.

But, as you point out, the equations in the original paper (and in Spivak 2010) assume a uniformly falling chain, so the velocities of their equations are uniformly downwards (Spivak derives $(dx/dt)^{2}=2/3g(x_{0}^{3}/x^{2}-x);d^{2}x/dx^{2}=-g/3(2x_{0}/x^{3}+1)$, and cites Calkin & March as getting $(dx/dt)^{2}=g(x_{0}^{2}/x-x);d^{2}x/dx^{2}=-g/2(x_{0}^{2}/x^{2}+1)$ where x is the height of the free end of the chain). 2601:9:3400:74:CC16:7C11:8B59:3F77 (talk) 17:45, 26 October 2014 (UTC)

What if the chain of beads is replaced with a soft string of uniform density?

By "soft", I mean the string can be bent to curvature of any given radius. Will the "fountain" still occur? --Roland (talk) 03:37, 8 July 2016 (UTC)

The explanation offered in the entry has been called into question

See this paper, Reexamining the Chain Fountain, whose abstract claims that the "kick" explanation of the chain fountain is wrong:

We show via proof-by-construction that the chain fountain, also known as the Mould effect, is a generic consequence of energy conserving dynamics of linear chains, similar to the extra acceleration observed for hanging or falling chains. Extracting a chain from its unentangled slack sitting on a table is much less energy dissipative than the claim of the classical scenario, postulated by Biggins and Warner[Proc. R. Soc. A 470, 20130689(2014)] as the starting point of their explanation of the chain fountain. As a result, their alleged upward kicks on the chain from the table as the chain is uplifted can at best be one of the possible factors in driving the fountain, if not totally irrelevant. We construct an efficient chain fountain with no upward kicks in Biggins and Warner’s sense, rather relying on the hanging chain dynamics. Simply put, the centrifugal force at the top of the fountain is responsible for maintaining the fountain. We argue that lateral motion of the chain in the slack plays a decisive role in the Mould effect.

They perform a clever experiment (photos are included) using a hanging chain to create a chain fountain despite there being no container to push off of. I think the explanation section of the entry needs to be completely revised in light of this paper.

— Preceding unsigned comment added by Nickg (talk • contribs) 14:59, 17 May 2019 (UTC)

Electroboom debate

Hi @Satvik123321: hopefully I have not discouraged you with the reverted edits. I know that this debate between Mould and Electroboom is going on, but in order for it to be included in Wikipedia we have to find a secondary source (anything outside YouTube, a news website for example) that has published something about it.--ReyHahn (talk) 14:35, 29 July 2021 (UTC)

Hi I'm in Kichumanna (talk) 16:33, 11 August 2021 (UTC)

By the way why do the chain rise up when we increase the hight Do any one know Kichumanna (talk) 16:35, 11 August 2021 (UTC)

Why is the chain fountain referred to as the "Mould Effect"?

Hi, why is the effect called the Mould Effect when some people have discovered the Chain Fountain years ago? As far as I know Steve Mould coined the term in his own videos, so it's not legitimate. BuildersHutGames (talk) 18:45, 22 February 2023 (UTC)

I think the article explains it well. The history of the name goes something like this: 1) older experiments did not notice the rise of the height of the chain when using ball chains 2) we have one exception maybe from a tournament, but even then Mould attracted more attention to the problem 3) it was officially named chain fountain in the only relevant paper in literature but the authors also gave credit to Mould and alternatively coined the term Mould effect.--ReyHahn (talk) 01:48, 23 February 2023 (UTC)It

Okay BuildersHutGames (talk) 04:32, 23 February 2023 (UTC)

cite 4

I can’t even find where in the video they do the stupid ball thing. Surely there are better videos that are not game shows. Can you put time in the YouTube link 204.107.216.7 (talk) 20:04, 3 April 2023 (UTC)

There are like 4 or more YouTube links in the article, you would have to be more specific.--ReyHahn (talk) 22:03, 3 April 2023 (UTC)

Polymer

I have seen a demonstration with a polymer. It should be mentioned that it also happens to polymers. -- Error (talk) 11:46, 13 November 2024 (UTC)

Could you provide a reference to such a demonstration?--ReyHahn (talk) 11:52, 13 November 2024 (UTC)

https://www.rtve.es/play/videos/orbita-laika/temporada-10-programa-6-ciencia-futbol/16325207/ 4:27-5:30 . I don't know it if it is region-locked. It asked me for a free login, but I clicked X and it played. If you cannot see it there, maybe it has already been uploaded elsewhere, though it was broadcasted yesterday night.

-- Error (talk) 12:04, 13 November 2024 (UTC)

I added some information on that. Great find.--ReyHahn (talk) 14:38, 13 November 2024 (UTC)