You have switches on the power outlets because you pump 220 volts out of
them and that would give quite a jolt<g>...but i do remember trying
unsuccessfully to get my laptop to power up for a while until i realized
that the outlet switch was off.
We spent a month in Oz last November and had a great time...You have a
wonderful country...we visited Sydney, Perth ,Adalaide, Augusta[sp], toured
the Margaret and Borassa Valleys, drank a lot of wonderful wine! We will be
back!! We have some good friends in Perth.
Well if you do, don't miss out on Queensland again huh?
I took our German exchange student to the Barrier Reef we did 12 dives
in three days, stunning stuff. That has to be worth a visit - at least
one of your Presidents has been there. That is about 2 hours flying
time of here, Fraser Island - A World Heritage location is about 3 hrs
drive. Steve Irwin's zoo is an hour drive away as are some of the best
beaches in the world.
And of course Brisbane itself, where you will have the services of a
The last time I checked, China was in the Northern Hemisphere therefore the
water swirls in the same direction as in North America (USA). The coriolis
effect goe in the other direction in the Southern Hemishphere.
So what? Wiki is mainly useful to get a quick overview of something
about which you know absolutely nothing. It is not an authoritative
source for much of anything except maybe wiki itself. There's a
reason that many colleges and high schools do not accept wiki as a
reference on term papers.
A colleague of mine actually tested this by watching water swirl down
drains in the northern hemisphere, near the equator, and the southern
hemisphere during various travels over a year or so. The results:
1. Swirl direction is highly sensitive to initial motion of the
water. If the water has any spin or motion before pulling the plug, it
will continue to swirl in that direction. To counter this effect, he
would fill the sink at night and not pull the plug until the next
2. IIRC, his results were not 100% but more like 80%, water in the NH
would swirl down the drain with an opposite sense than in the SH
(can't remember which one was CC and which was CCW).
So based on his observations, the effect is weak, but it is there.
Having done the same experiments myself, and using coriolis and geostrophic
winds in air navigation,
http://ww2010.atmos.uiuc.edu /(Gh)/guides/mtr/fw/geos.rxml your friend is
tugging at your trouser leg.
Northern hemisphere, when the wind's to your back the low's to your left.
Good mnemonic for weather prediction and coriolis.
No kidding. That piece of crap operation has information which is only
as good as the most recent edit. In 30 seconds it can be
trashed--subtley or precipitously--rendering it utterly worthless. An
"information resource" which is potentially worthless is essentially,
I wouldn't call it "utterly worthless". It's very handy for answering
questions like "Who is this Paris Hilton person that everybody is on
about" or "What in the H-E-double-toothpicks is a bunyip". Not the
basis for a scholarly paper, but tells enough to satisfy idle
curiosity and let me determine whether I want to delve deeper.
Mekon wrote: > > Roger Woehl has brought this to us :
". The coriolis effect goes in the other direction in the Southern
Is it possible to detect the Earth's rotation in a draining sink?
Yes, but it is very difficult. Because the Coriolis force is so
small, one must go to extraordinary lengths to detect it. But, it has
been done. You cannot use an ordinary sink for it lacks the requisite
circular symmetry: its oval shape and off-center drain render any
results suspect. Those who have succeeded used a smooth pan of about
one meter in diameter with a very small hole in the center. A stopper
(which could be removed from below so as to not introduce any spurious
motion) blocked the hole while the pan was being filled with water.
The water was then allowed to sit undisturbed for perhaps a week to
let all of the motion die out which was introduced during filling.
Then, the stopper was removed (from below). Because the hole was very
small, the pan drained slowly indeed. This was necessary, because it
takes hours before the tiny Coriolis force could develop sufficient
deviation in the draining water for it to produce a circular flow.
With these procedures, it was found that the rotation was always
http://ww2010.atmos.uiuc.edu /(Gh)/guides/mtr/fw/crls.rxml [University
of Illinois at Urbana-Champaign]
Yes WIKI is not necessarily "the authority,"but it does comport with
the other reliable sources in this instance, Moreover, given the
history of the effect and its original application, the "determined by
the force of the water entering the commode" approach makes sense.
Indee, why would the water in a vessel NOT ROTATE even absent an open
drain if this effect applied at the macro level?
But we digress from the question inspiring this dialog, no?
That particular site goes on about how the force is "small" and how
that is because the Earth "rotates slowly". What I don't see there is
an estimate of the magnitude. While I don't have the time or
inclination to go back to my physics texts and work out the
calculation there's something bothersome about the notion that "it
takes hours before the tiny force could develop sufficient deviation".
Simple experiment--start the water in a sink swirling one
direction--watch it as it drains, see if it keeps going that
direction. Then try it the other way and see it it happens. If it
reverses then that knocks the notion that it's due to preexisting
rotation into a cocked hat.
Why would it not rotate? Because if the water in the vessel is not
moving then it's not subject to the Coriolis force. There seems to be
a major misconception about the nature of the Coriolis force inherent
in that statement.
From a triple digit channel on cable TV, there was this program:
A long time ago during the Greek civilization (500BC??) this guy invents a
bilge pump for ships at sea. (you know, the ships that has all them slaves
pulling on oar's.) It is a one man crank type of thing that looked like a
screw set inside a hollow wood tube (auger.) The edges of the inner screw
shaft was water tight against the outer tube. The bottom tip was at the
bottom of the ship and as the sailor (slave?) turned the crank the water was
lifted up and out of the many ship. This was the first cylindar wedge.
Later, the ship board propellor, and aircraft propellor would take on the
same shape as a section of the cylindar wedge. Telephone pole post hole
diggers (augers) use the same shape and rotation today.
Archimedes Screw pump:
graphic on right hand side midway down.
Looking at the model they built for the TV show crosswise, and you see the
shape of a screw (auger.) The acient version of this was also turned in a
right hand clock wise manner. IIRC, they had an ancient drawing of the
bilge pump showing the 'righty-tighty' (as in tidy clean up, or ship-shape)
turning of the cylindar wedged shaped bilge pump.
Related to today's screw threading? Your guess as good as mine. But the
treading of a screw does go back to before Roman Empire time. The problem
is, there is only a small handful still here this NG that remember so long
Never realized that Archimedes developed that pump originally as a
bilge pump. Clever fellows those old Greeks.
FWIW Greek and Roman warships did not use slaves for rowers--that
didn't come until the Middle Ages and the advent of gunpowder, which
changed tactics from "ram and board" to "standoff and shoot".
Merchant ships were not in general powered by oars at all.
Becauuuuuuuuse, Righty Tighty Lefty Loosey was the official national
standard developed before the direction of the screw was decided upon.
Screw direction was anticipated as being a problem and therefore the "easy
to remember" safety reminder was created before the direction of the screw
was determined. I'm quite sure that the government was put in charge of
developing this standard and the tax burden on its citizens was enormous,
resulting in a debt that is still nagging us to this day. ;~)
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