Re:Toilet bowl physics ???

[Leigh Palmer <palmer@sfu.ca>]

> The explanation of surface tension being responsible for the clustering
> of small pieces of hair on the surface of water is not clear. How does an
> arbitrarily chosen piece "know" that it is not alone? Surfce tension is
> due to water. And it is the same on its both sides.
>                                                          Ludwik Kowalski

Surface tension is likely responsible for the initial spreading. I
think each hair makes a little oily raft on which it floats
initially, and these oily rafts each spread out as far as possible*.
I had never observed the second effect Ludwik mentioned, but it
might have to do with the absorption of water by the hair itself.
I do know that hair can absorb water. After it has done so they may
be hydrophilic and work their way out of the hydrophobic oily raft,
aggregating at the boundaries of the former rafts, or be held
together by their mutual disaffinity for the oil.

It's a wild guess, but there may be some evidence to be seen in
the pattern. I can't check. I shave with a blade in the shower,
and I'm not going to buy an electric shaver at this stage in life.

Leigh

*They are one molecule thick if that is possible.