- #1
Brinx
- 69
- 1
Apologies if this has been discussed in other threads already. I did a quick search on 'chain fountain' and got no hits.
If you coil a length of chain into a container and let it slip out over the lip under its own weight, it will start to form an arc through the air, without touching the lip of the container. See this youtube movie wherein this phenomenon is demonstrated and discussed:
I am having trouble believing the explanation that is put forward in that clip. Reaction forces from the 'table' (or in this case the surface of rest of the chain filling the container) do not perform any work and cannot cause the chain links to push one another upward into an arc shape.
I lean towards the explanation (not quite sure yet) that it is an inertial effect: as the chain gets dragged out of the container by the part that is slipping over the lip, it accelerates as more and more mass is falling down (and accelerating) on the other side. As it needs to change directions quite rapidly as it clears the lip (from upwards to downwards, with a small turning radius), the rotational inertia of the links causes them to whip out their rear end (the links have finite lengths) and pull the following link up a bit. The next link does the same, and the flow of links reaches an equilibrium height above the lip of the container.
I suppose I should make it more clear by providing a diagram of the situation. In any case, I would welcome some discussion on this interesting phenomenon. I have already ordered a chain online to experiment myself. :)
If you coil a length of chain into a container and let it slip out over the lip under its own weight, it will start to form an arc through the air, without touching the lip of the container. See this youtube movie wherein this phenomenon is demonstrated and discussed:
I am having trouble believing the explanation that is put forward in that clip. Reaction forces from the 'table' (or in this case the surface of rest of the chain filling the container) do not perform any work and cannot cause the chain links to push one another upward into an arc shape.
I lean towards the explanation (not quite sure yet) that it is an inertial effect: as the chain gets dragged out of the container by the part that is slipping over the lip, it accelerates as more and more mass is falling down (and accelerating) on the other side. As it needs to change directions quite rapidly as it clears the lip (from upwards to downwards, with a small turning radius), the rotational inertia of the links causes them to whip out their rear end (the links have finite lengths) and pull the following link up a bit. The next link does the same, and the flow of links reaches an equilibrium height above the lip of the container.
I suppose I should make it more clear by providing a diagram of the situation. In any case, I would welcome some discussion on this interesting phenomenon. I have already ordered a chain online to experiment myself. :)
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