From: glen mccready
To: Dead Beef <0xdeadbeef@substance.abuse.blackdown.org>,
Garry Turcotte , Gordon B Bell
Date: Wed, 19 Jul 1995 15:50:23 -0400
---------- Forwarded message ----------
Date: Wed, 19 Jul 1995 13:35:02 -0400
From: Keith Bostic <bostic@CS.Berkeley.EDU>
To: /dev/null@python.bostic.com
Subject: ATTN JMS: Direction of Toilet Swirl?
Forwarded-by: Peter Langston <psl@acm.org>
Forwarded-by: mbkomor@remarque.berkeley.edu (m.b.komor)
From: gharlane@ccshp1.ccs.csus.edu
In <DBoEGI.K2K@thomsoft.com> kst@thomsoft.com (Keith Thompson) writes:
> My understanding is that the Coriolis force caused by the Earth's rotation
> is far too weak to have any significant effect on the swirling of water
> in toilets and sinks. The effect might be measurable with sufficiently
> sensitive instruments under ideal circumstances, but it's normally masked
> by the effects of the shape of the toilet or sink and any initial motion
> in the water. Remember that the Earth will rotate only about one minute
> of arc in the time it takes to flush.
Your "understanding" is correct. In one of the more classic
bored-physicist experiments (a group of physicists bound for Antarctica
during the now-forgotten "International Geophysical Year," about 37 years
ago) a group of PhD's tried to design an experiment using a very large
tank of very still water on shipboard, trying to see if they could
determine with reasonable accuracy when they crossed the Equator. With
the time and equipment they had available, they were unable to invent an
experimental regime that came anywhere close to producing reasonable
results.
As an aside, you might also try paying attention to any whirlwinds you
encounter; a good percentage are spinning in the opposite direction than
the Myth would lead you to expect.
In practice, the direction of spin in a fluid medium, air or water, seems
to be more based on the original motion components of the fluid than on
which hemisphere the funnel happens to be in.
I notice that Chris Carter, at the "X-FILES," subscribes to this Urban
Myth as well; in tonight's re-run (one of their better shows) Agent Mulder
detects the Presence Of Evil by noticing that the water in a drain is
spinning what he thinks is the wrong way. (Oh, well; at least he was
polite to the Wiccans, and didn't confuse them with demon-worshipping
psychos; you can't win 'em all.)
> Some friends and I once performed an experiment at a party. We filled
> the bathroom sink with water and added a few bits of paper to show any
> motion of the water. We let the water sit for an hour or so, to let
> any currents die out, and then opened the drain. It drained straight
> down with no swirling. (Yes, it was a fun party; why do you ask?)
Sounds like you go to the same kind of parties I do. The last really
good party I attended, the hostess had arranged for us to see a preview
copy of a movie we'd all contributed material to, but her VCR/projector
was very crudely aligned. So the bunch of us tore it down, matched the
adjustments, and did a *proper* convergence on it before we watched the
video tape. There was a moment of acute panic on the part of the
hostess when she came back down to the screening room to see how we were
getting along, and found twenty kilobucks' worth of Home Theater System
spread all over the floor in pieces.
Hostess' Husband: "I *TOLD* you not to leave any tools out, with
this bunch in the house!"
Hostess: "I didn't! They all had Swiss Army Knives and
Little Screwdrivers!"
Hostess' Husband: "God, look at this mess. Can't they just drink
and bust things, like normal party guests?"
... The front-projection unit was at better-than-factory alignment when
we were done with it. It really was the best sixty-inch projection TV
display I'd ever seen, after it was properly degaussed, compensated, and
converged. (And our movie looked great, thank you very much.) However,
at the next party at that house, the butler requested that we check
"weapons and tools" at the door. (We ignored him.)
> Hopefully someone who knows more than I do will correct me if I'm wrong.
You weren't.
> Inevitably someone who knows less than I do will correct me if I'm right.
Count on it; if it's a form of behavior indistinguishable from bull-headed
obtusity, it's normal for the Net.