  If a long chain is held in a pot elevated a distance h_1 above the floor, and
the end of the chain is then dragged over the rim of the pot and released, the
chain flows under gravity down into a pile on the floor. Not only does the
chain flow out of the pot, it also leaps above the pot in a "chain-fountain". I
predict and observe that if the pot is held at an angle to the vertical the
steady state shape of the fountain is an inverted catenary, and discuss how to
apply boundary conditions to this solution. In the case of a level pot, the
fountain shape is completely vertical. In this case I predict and observe both
how fast the fountain grows to its steady state hight, and how it grows
quadratically in time if there is no floor. The fountain is driven by an
anomalous push force from the pot that acts on the link of chain about to come
into motion. I confirm this by designing two new chains, one consisting of
hollow cylinders threaded on a string and one consisting of heavy beads
separated by long flexible threads. The former is predicted to produce a
pot-push and hence a fountain, while the latter will not. I confirm these
predictions experimentally. Finally I directly observe the anomalous push in a
horizontal chain-pick up experiment.

Classical Physics;Popular Physics