That's cool.

Very.

Want.

Animavore wrote:Want.

You can make. As I said on the other thread about this you can buy such chain at the local diy, or at least, I can. I have some as pull cords for the bathroom. Although I think his might be a bit fatter. I wonder if that would make a difference?

I would posit that the falling chain does not get 'heavier' from the berginning to the end... after all, the 'puddle' of chain on the ground becomes larger, but since the ground is taking that weight, the chain's weight is distributed through the resting mass.

The weight of the chain that is *falling* reaches a relatively steady state... the weight determined by the length (mass) of chain in motion, from beaker lip to ground.

An object at rest tends to remain at rest until acted upon. Thus, the chain's 'nonmoving' portions (the 'puddle' on the ground, and the bottom of the chain in the beaker are gaining and losing *density* (in terms of space occupied) but I'd say the mass of both remains the same. The distribution changes, creating the energy that forms the loop. It's the segment in motion at any given time that's affected. The *speed* of the falling chain remains fairly constant.

Now... take that experiment to the top of a tall building. Taller, by say ten inches, than the chain's length. Thus, there is no time when the chain 's tip is in contact with the ground, creating a portion at rest. I suspect that the falling speed of the chain will increase because the falling portion - the ENTIRE part of the chain in motion - is, indeed gaining mass. No part of it is supported and the fall speed would increase, approaching truly dangerous terminal velocity in terms of loose metal whipping about. You would not, however, find waves forming, I'd think, because the tension is not reciprocal (?) the downward momentum of the chain is taking all the energy it can. I suspect that the chain might not 'levitate' at the beaker's edge, but would fall straight down, scoring the material of the beaker. I may be all wet there. IN terms of physics, I am an untrained layman.

I've only had a high school's memory of physics, and that, 43 years ago. I'm probably making an ignoramus of myself. Still, the video is definitely cool!

Swan

More on the self siphoning bead chain thing...



The slow motion version (also linked in the OP) and a shorter demo of the bead chain experiment have a combined 3,855,115 views.


Self siphoning beads


Here's someone, Aimee Whitcroft; a participant in the thread on this page about the bead chain thing, who tried it with lightweight plastic beads.
She made a video showing it worked.


It also caught the attention of Professor Mark Warner of the Cavendish Laboratory and the Rutherford School Physics Project, and Dr John Biggins, of the Cavendish Laboratory, and Trinity Hall, Cambridge.

The problem of the chain fountain was revealed by BBC Science presenter Steve Mould. 2.8 million people have watched his video demonstration of a chain appearing to defy gravity by first leaping out of a pot before falling to the ground.

Professor Mark Warner and Dr John Biggins have published the first formal explanation of the physics behind this puzzle in Proceedings of the Royal Society A.
http://www.cam.ac.uk/news/understanding ... artnership

Here are the links -

Understanding the chain fountain
J. S. Biggins and M. Warner
Published 15 January 2014

Abstract
If a chain is initially at rest in a beaker at a height h1 above the ground, and the end of the chain is pulled over the rim of the beaker and down towards the ground and then released, the chain will spontaneously ‘flow’ out of the beaker under gravity. Furthermore, the beads do not simply drag over the edge of the beaker but form a fountain reaching a height h2 above it. We show that the formation of a fountain requires that the beads come into motion not only by being pulled upwards by the part of the chain immediately above the pile, but also by being pushed upwards by an anomalous reaction force from the pile of stationary chain. We propose possible origins for this force, argue that its magnitude will be proportional to the square of the chain velocity and predict and verify experimentally that h2∝h1.
http://rspa.royalsocietypublishing.org/ ... 7ba5938a2a

Full Text

PDF download

They ^^^ also made a video, published on the Royal Society youtube channel, demonstrating the physics. One of the interesting things they did, relating to many of the comments on the various comment threads on pages that link to the original Steve Mould video, was drop the chain from a significant height - 10m over a balcony onto a descending staircase inside the Royal Society building.
Presumably they did it to demonstrate that the 'rising loop' is higher with greater velocity of the falling chain, but one suspects they did it also because it was fun &... they could.



Understanding the chain fountain
The Royal Society


Here's another (short) bonus video, nothing to do with the 'self siphoning bead chain fountain', but more so with waves in a moving chain and, at the end, fun with physics.



Waves On A Chain - MIT Department of Physics

It's the work of the devil!

Ironclad wrote:It's the work of the devil!

The devil has all the coolest shit.

It all looks to me as though it's because each link is being dragged in the direction that the one before it is dragged, with a vector alteration caused by it's own resistance (inertia?).

What's interesting to me is that there is a class of fluids called 'viscoelastic' that have a tendency to flow against gravity under the influence of elasticity in what are modeled as chain-like molecules that possess internally-generated restoring forces because their lower-energy state (lower free energy state would be more technically-correct) is to be coiled up rather than stretched straight. An elastic band warms up when you stretch and relax it repeatedly.

There's nothing analogous to this internal restoring force in the bead-chain experiment, except for the 'kick' supplied from the links of the bead chain and the bottom of the beaker reacting against one another. In this case, we're analysing it in terms of rigid-body mechanics and in the viscoelastic case we are analysing it in terms of forces that arise in internal deformation. I find the parallels fascinating, even though the details of the equations of motion do not have analogous terms.