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Re: [T3] Coriolis Effect Down Under

On 23 Jul 99, at 5:35, DGaries808@aol.com wrote:

> Is it true that toilet water swirls clockwise in Australia?  It should be 
> that way in Australia, southern Africa, and south-South America.  For people 
> who live directly on the Equator, water should flush straight down.  I don't 
> know what effect that is.  It would be interesting to find out, though.

The Coriolis effect is real and it is responsible for the fact that 
tornados and hurricanes turn one way in the northern hemisphere and 
the other way in the south. The effect must be taken into account for 
the aiming of long range artillery shells, too.

But the effect is much too weak to affect the water in our toilets 
even though this has been taught as "fact" in high school pclasses for generations. 

Someone did a study of this a few years ago for one of the physics 
journals. Since the Coriolis effect is stronger for larger scales, 
they made a rather large pool, 12-20 feet in diameter and just a few 
inches deep, with a central drain, and tested it to see which way it 
swirled when the drain valve was opened. To get rid of the effect of 
any angular momentum due to filling, they finally resorted to letting 
the water sit for several days before they "flushed." Even then the 
results were random.

Finally they tried stirring the pool after filling then let it sit 
for several days. What they discovered is that there was a 100% 
corelation between the direction that the pool had last been moving 
and the direction that it swirled when emptied. I don't think they 
let it sit for more than a week, but they had done some calculations 
that seemed to show that the viscosity of the water should have 
damped out virtually all of the angular momentum that the stirring 
put in, Still that was the factor that dominated.

So your sink and toilet probably swirl in the same direction that 
they were filled.


Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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