Attn: Southern Hemisphere folks

[Power Giant]

When one flushes the toilet in the southern hemisphere, which way does the water spin: clockwise, or counter-clockwise? I'm dying to know.

[Faiaoga]

Living in the Southern Hemisphere (about 14 degrees south), I found that the water spin direction depended upon how the bucket was tilted when the water was poured in.. As a Peace Corps volunteer in a Samoan village, we had water seal toilets made of concrete. The water reservoir was an old oil drum filled with a hose, and you had to use a small bucket to get water for pouring into the toilet bowl - no sissified porcelain toilets with piped water and float valves. I think the idea that water goes out differently when you live south of the equator is an "old wives tale".

[WolfVanZandt]

Look up Coriolis Effect. The same thing that drives hurricanes and tornadoes in the counterclockwise direction and makes rivers and streams and trickles on a flat glass pane to meander to the left, all other things held constant, is what causes vortexes in the Southern Hemisphere to attempt to go in the other direction, all other things held constant.

[Rick]

It would be entirely dependent on how the toilet was constructed. If it sends water in a clockwise direction then that's the direction it will spin. Or...it may not spin at all. Water is controlled by the vessel that contains it much more than any natural effects.

[WolfVanZandt]

Aye, and that's why I emphasized "all other things held constant". Toilets tend to shoot water in at a particular angle. On the other hand, water just running out of a drain under it's own force will be guided by the Coriolis effect and that has to do with the fact that the Earth is spinning out from under it and a fairly high rate of speed. It is "parlor science" that toilets spin according to the Coriolis effect because there are forces making it go in, possibly, other directions (Coriolis is fairly weak), but it is some effect so it's not true that "It would be entirely dependent on how the toilet was constructed." "Entirely" is too strong a word. What is absolutely true is, "Water is controlled by the vessel that contains it much more than any natural effects," (the operant term is "much more than") when that vessel is not a passive vessel - in other words, when that vessel actively forces the water in some particular direction.

What you actually see in a drain is amplification of initial motion by gravity and rotational forces. If the water is allowed to become still before it is let out of the drain, then the only force present at the beginning is the Coriolis effect and that is the effect that guides the vortex. If there is some other force initially determining the direction of flow, that force will be amplified.

Nature is chaos rich - that means that initial conditions in natural processes are much more relevant to their progression than would be true under controlled conditions. Nothing is simple in nature. Large effects in the world such as hurricanes and tornadoes and river meanders match the earth's rotation a lot closer than tiny water vortexes and drops of water flowing on glass planes so the Coriolis effect is much more likely to "grab on and spin" the large things than the smaller ones. Its like the different between you trying to spin a bicycle wheel like a top with your hands and trying to spin a 1 inch in diameter toy top with your hands. For the top, you need something smaller like a string or your fingers (instead of your hands). Coriolis is a "big effect".

Nevertheless, Coriolis, under controlled conditions, can be observed in both the drain and the drop, so it is present and it does have an effect.

[JPGreco]

All things cannot be held constant though, that's an absurdity. Water flowing out of a drain under gravity alone will be mostly dependent on any initial motion of the water, which in small containers is dependent on other factors to a much greater degree than the coriollis effect and the construction of the vessel itself. If the coriolis effect was that strong, you would see any contained water spinning in the appropriate direction. Sit a bucket of water on the counter for a few days with a rubber duck floating on the surface and see if it's being dragged around in a circle.

Probably the only way you could get a bucket of water to react via the coriolis effect when draining would be if the container was absolutely perfectly smooth and zero friction surface. Each container would have to be at the same exact lattitude, altitude, and under the same exact gravitational constant, held at the same exact constant temperature in a complete vacuum. Any force that requires that much to become the dominant predictor of how the water will react once the drain plug is pulled isn't strong enough to have any relevance in real world application.

It's on par with the difference in weight of an object on earth when the moon is at perigee and apogee.

[kyratshooter]

It is really amazing the things people will talk about/argue over when politics and religion are taken off the table!

[hunter63]

It is really amazing the things people will talk about/argue over when politics and religion are taken off the table!

LOL....No ship......
Just had the laptop in the shop....picked up a bunch opf pop-ups stuff while trying to down load a catalog for the Cobray derringer.

The Geek asked if I wanted to spend a bunch of money for a back up before they started playing with it.

Told him, "No...Most all my pic's, doc and music already backed up....Be sides (and I used Ricks line)...
"With all the worlds knowledge, at anyone finger tips 365 24/7.......We watch cats playing piano, and argue with strangers...."

....I thought he was gonna choke......

Anyway, southern hemisphere, pull plug, water goes counter clockwise....or Old wives tale?

Who made that old wife an expert anyway........(looks around to see if I'm being watched)?

[JPGreco]

Sticking with old wives tale or coincidence, not due to coriolis

[Rick]

"Entirely" is too strong a word

Nu uh......

[WolfVanZandt]

Not really, Greco, and, honestly, if you look it up, you'll see the same thing. For instance, if you let the surface of water in a tank come to rest and then pull the plug from the bottom so that the surface isn't disturbed, then the Coriolis effect will be prominent. What I'm saying is that the Coriolis effect will rarely be prominent in small events - under laboratory conditions, all other things can be made equal (or, at least enough to see the Coriolis effect). But it is there regardless of whether it's there strong enough to direct the motion of a small vortex. It's not "entirely" missing.

And, Hunter, it's not an old wives tale - it's parlor science, which is just about as bad. There are even textbooks that say that water leaves a drain counterclockwise in the Northern Hemisphere and clockwise in the Southern.

[ElevenBravo]

Ive got a problem, my water doesnt spin, it shots straight for the hole... Should I be concerned? Should I take action?

EB

[hunter63]

...........
And, Hunter, it's not an old wives tale - it's parlor science, which is just about as bad. There are even textbooks that say that water leaves a drain counterclockwise in the Northern Hemisphere and clockwise in the Southern.

OK thanks for clearing that up.....
(someone outta get ahold of the old wife and straighten her out.....)