A request regarding Newton's beads/chain fountain phenomenon

[FIL]

I am wondering if any of the scientists here with access to the necessary equipment would be willing to demonstrate this phenomenon under vacuum.

A chamber of appropriate height or rigging the beads to a drill(as shown in some variations of the experiment) should suffice.

My reason for this request is that in all variations of this phenomenon I have been able to find, no one has considered the medium through which the beads must travel and therefore the fluid dynamics that come into play. Specifically, I have some intuition that Bernoulli's principle may be a primary factor.

Part of the reason I suspect this is that I've witnessed this phenomenon with synthetic rope frequently. I'm curious about science but I'm not a scientist by any means, I'm a roofer by trade, and as such handle ropes regularly. This causes me to question the explanation put forward regarding the beaded segments acting as levers and creating a reactive force in the beaker. I think we're observing an oddity of fluid dynamics associated with an elongated elastic object moving through the air.

So I'm hoping someone here with the means is interested enough to consider testing whether this effect still occurs in vacuum.

Thank you.

 

[berkeman]

A chamber of appropriate height or rigging the beads to a drill(as shown in some variations of the experiment) should suffice.

Welcome to PF.

Can you please post a link or two to what you are asking about? It always helps to post links to your reading here, so we can see what you have been researching. Thanks.

 

[FIL]

Welcome to PF.

Can you please post a link or two to what you are asking about? It always helps to post links to your reading here, so we can see what you have been researching. Thanks.

Sorry, yes a link would be helpful.

Specifically how the chain rises into the air is what I'm curious about regarding fluid dynamics.https://en.m.wikipedia.org/wiki/Chain_fountain

 

[Keith_McClary]

Of course, there are youtubes:

 

[FIL]

I've seen those explanations, but I don't see how it applies to a rope which can produce the same effect. That's why I'm curious to see what the result would be in vacuum.

 

[A.T.]

I don't see how it applies to a rope

it applies to anything with limted bendability.

 

[FIL]

I dislike such absolute statements, clearly it would not work with common copper wire for instance. Further, the explanation of the ball links acting as levers is incomplete or outright incorrect. Otherwise the macaroni chain would have created a more pronounced fountain than the beaded chains do and would not need the benefit of a different container to produce the much less impressive fountain shown.

I would appreciate some explanation as to why the hypothesis that the medium through which the chain travels plays an important role is unreasonable if that's your position. It seems quite logical to me that it does. Examples of common experiences come from better fuel economy when one closely follows a vehicle in front of them, and how in baseball the fluid dynamics are the reason trick pitches are even possible.

 

[A.T.]

I would appreciate some explanation as to why the hypothesis that the medium through which the chain travels plays an important role is unreasonable

It's your job to show quantitatively that it could be important, at least with some estimates.

Note that several people have done numerical simulations of this, showing that the bendability plays a key role for the foutain height. You can ask them if including aerodynamics was needed at all to reproduce the effect.

 

[FIL]

I don't have the necessary education to formulate the proposal in the way you're asking me to. It was my hope that the professionals here with access to the equipment necessary would be curious enough to see if performing the experiment under vacuum changes anything. I understand you may be accustomed to lay people speculating on things and insinuating bogus theories or crank science and in such cases demanding a formal proposal is fair. However I'm here in good faith, not insinuating anything controversial as far as I can tell, and would appreciate some leniency in this regard.

Perhaps the chain fountain phenomenon isn't as much of a curiosity to people with a solid grasp of physics, but I was under the impression this is still a bit of a puzzle and felt I made a good point regarding the current explanation being incomplete considering the performance of the macaroni chain and the container they used to demonstrate it.

If what I'm asking is inappropriate to this forum I apologize, and would appreciate if anyone could suggest a more appropriate site to make my request.

 

[PeroK]

It was my hope that the professionals here with access to the equipment necessary would be curious enough to see if performing the experiment under vacuum changes anything.

I'm not a professional, and don't have access to a vacuum chamber.

You could email your nearest university physics department and see what they say. Would you personally be prepared to pay for the lab time to satisfy your curiosity?

 

[A.T.]

I am wondering if any of the scientists here with access to the necessary equipment would be willing to demonstrate this phenomenon under vacuum.

Here a simulation for different bending limits between the links. You can ask the author if air was included in the simulation:

 

[Keith_McClary]

if performing the experiment under vacuum changes anything

Alternatively, one could try fluids other than air. That might be easier/cheaper.

 

[FIL]

Here a simulation for different bending limits between the links. You can ask the author if air was included in the simulation:

Thank you, I haven't seen that video. I'll send the creator a message.

Alternatively, one could try fluids other than air. That might be easier/cheaper.

That's an interesting idea and potentially something I could rig up myself, thanks.

 

[A.T.]

This causes me to question the explanation put forward regarding the beaded segments acting as levers and creating a reactive force in the beaker.

The theory by Biggins/Warner/Mould is:

A requirement for the fountain is the additional force from the support that accounts for the weight of the chain going up the fountain. For the beaker scenario this force is created by the "lever effect". But in other scenarios it might be created by other means. See Steve's latest video at 15:30:

See also the simulations at 19:10, where removing the support prevents the fountain:

Here a similar comparison for the beaker scenario at 9:26:

 

[A.T.]

Further, the explanation of the ball links acting as levers is incomplete or outright incorrect. Otherwise the macaroni chain would have created a more pronounced fountain than the beaded chains do ...

The performance of the macaroni chain is addressed here at 12:00:

I don't see how it applies to a rope which can produce the same effect.

Regarding rope and other non rigid vesions see the simulation at 10:12:

 

[A.T.]

There is a new video by ElectroBOOM, where he concedes the bet with Steve Mould, and agrees about the additional force from the support.

But he still disagrees about how that force is generated in the case of the horizontal rod support. He claims that friction is necessary for that:

1) If he agrees with the additional vertical force, then it can only come from the normal contact force. Unless he wants to claim that friction is asymmetrical at the sides.

2) His friction theory could be tested in the simulation below, where you can eliminate it (if it was included at all)

 

[Swamp Thing]

Now that the dust has settled, and Electroboom has pretty much conceded that Steve was (mostly) right ... I still have a question.

Which statement best reflects the true situation:

[1] A chain fountain will always need an upward impulse from the supporting surface or structure, acting on each successive bead.

OR

[2] In all the variations discussed in this series of videos and their linked sources, the upward reaction from the support certainly played an essential role... but it is possible to set up experiments where that is not required.

I am asking about possibility [2] because I am somewhat hopeful that I can come up with a setup where the fountain will work well, but where the support reaction would be clearly seen to be irrelevant. When my notion crystallises a bit more, I may post it here. But I'm curious whether anyone else considers [2] to be a feasible thing.