Today I found out what hemisphere you are in does not affect the way water spins down your drain.
So why do some textbooks, most tour guides, and pretty much all TV shows like The Simpsons get it wrong? The myth that water in your drain will spin differently depending on what hemisphere you are in primarily stems from taking a very real physical precept, namely the Coriolis Effect, and applying it to a situation that it doesn’t make sense with.
The Coriolis Effect, named after Fustav Gaspard de Coriolis (1792-1843) who published a paper in 1835 on the subject, is basically an apparent force relative to the Earth’s surface that causes objects to appear as if they are moving in somewhat of a curved path. What’s actually happening is they are moving straight and it is the Earth turning that makes it look like they are curving. So more practically, it causes apparent deflection of moving objects to the right in the Northern Hemisphere; to the Left in the Southern Hemisphere; and no apparent deflection on the equator.
So it seems reasonable enough to think that the Coriolis Effect would affect the way the water spins down the drain. Indeed, things such as hurricanes and other large cyclonic systems are very much affected by the Coriolis Effect in terms of which way they spin. However, a hurricane might literally be 500 miles in diameter and last for many days; your sink or toilet is very small in comparison and the time the Coriolis Effect has to influence the draining water is very small as well. In fact, when we are talking draining sinks, toilets, and bathtubs, the size and time scale is so small that the Coriolis Effect force is practically non-existent in terms of effecting the water in any way, especially when compared to the other forces in play here like the shape of the sink, the way the jets are pointed in the toilet, and things of this nature.
In this case, the Coriolis Effect has about the same affect on the swirling water in your toilet as a butterfly’s wings flapping have on a Tornado.
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you… are…an…idiot…
have you ever been south of the equator?
When I lived in New Zealand, I observed this very effect.
once again….
you… are…an…idiot…
I teach high school Earth Science, and used to teach that the water rotated differently in the hemispheres. Until one day I decided to test the theory in our own ladies room of the school. Guess what? Two out of the six toilets had water that rotated counter-clockwise, while the others rotated clockwise. THEN I actually researched the Coriolis Effect (instead of just blindly teaching potentially bad science)and had to apologize to my classes. It did however turn in to an excellent lesson on debunking myths.
Hi from Australia. I concur with Jim – the water DOES rotate the opposite direction when going down the drain here.
@jim: sometimes personal experience can fool you, particularly when it comes to physics and things of this nature. Check this out: http://www.snopes.com/science/coriolis.asp
If you still aren’t convinced you can look at the mathematical explanation and see that the Coriolis Effect affects the water in your drain a few orders of magnitude less than the combined other forces in your drain; so again, like a butterfly’s wings flapping against a tornado: http://en.wikipedia.org/wiki/Coriolis_effect
I live very close to the equator, and have seen how water swirls indifferent directions when the plug is pulled 20 m to the south and 20 m to the north of the equator. Believe it or not, precisely on the equator, the water goes straight down the plug! You probably won’t believe me, but I have seen it demonstrated several times.
Wow!!! I can’t believe this. Daven, you say that it is so. Just that it would be very hard to observe. So why even say that it isn’t true? Jim may actually be overstating your intelligence. If you are going to hold that a certain result will occur you should not clearly relate opposing facts.
@John: The water will swirl the way the jets are pointed or with how the sink is shaped vs. how the water enters it and other such factors. The Coriolis effect isn’t strong enough on this scale and time-span. It has about the same effect as you waving a hand fan at a tornado. Feel free to read up on the math behind it to see just how little force the Coriolis effect has on this scale/time if you don’t want to take my word for it.
Gidday. I’m from Oz & I’ve been watching water spin clockwise all my life.
However. I made a point of observing during visits to England and Germany.
The water spun in the anti-clockwise direction.
Despite the Coriolis effect being debunked. Is this the only explanation ?
There is much we don’t know about water & we probably wouldn’t build damns if we knew more.
Surely human anecdotal evidence counts for something.
With all due respect, I say it’s true and the answers probably won’t be found in a maths book.
all those who are saying it’s true seem to be ignoring all the variables that account for the different directions the water goes ie. what daven has already stated; the direction the jets are pointed, the shape of the container etc. etc. Listen….. physics has already proven that the hemisphere you are in has nothing to do with the which way your water drains, so if you want to continue believing in things that have already been disproven, enjoy your time at sea, because your going fall off the edge of your flat world!! But the good news is, as your falling you can finally swallow all the gum you want, because you wont have to worry about it taking 7 years to pass through your system!!!!
lol @ jim …
it is amusing how many people are not able to acknowledge the fact that something they believed in their whole lives is proven (by science, math and logic) to be not true at all. and we’re talking about stupid, pointless thing as direction of water spinning in drains.. now try to talk some sense into religious people.
I tried this out in my bathroom and I live in the northern hemisphere. The shower water spins clockwise, but the toilet and sink spin counter-clockwise. Case closed for me.
It seems the problem people have with accepting this explanation is very similar to the problem they have with global warming. Eg. “But we had a really cold winter this year – and the last one” or “I don’t notice it getting any warmer – global warming must be a myth”. Scientific experimentation trumps individual, one-off, small sample experience – if we can’t trust science on these questions it becomes every man/woman’s opinion for themselves. I’ve got the humility to accept when data proves me wrong – I hope most other people do too.
Nope. The coriolis effect can indeed affect the direction of angular momentum in draining water.
Unlike clapping in a tornado or the flap of a butterfly wing in a hurricane, water draining in a sink is an amplifier of angular momentum.
The tiniest angular momentum differential between opposite sides of the drain will become amplified by the the inertial component of spin. Spin influence becomes cumulative and amplified. And self-sustaining.
You can observe this yourself when you see that water spinning around the drain spins so fast that centrifugal force holds the water up against the sides of the toilet bowl and inhibits draining. That causes a slowdown of spin and re-establishes drainage, but now a balance is reached and maintained, where spin and drainage is maintained at a steady rate until all the water is gone.
Among other things, this means that – yep, Coriolis effect, however slight, does influence the spin direction of draining water in the hemispheres.
Coriolis effect also makes flushing toilets marginally inefficient. Too much water is wasted going around in circles around the bowl when it should be flushing stuff straight down the drain.
@Bananas: And your sources for this are?
im a fith grader and at my school we are doing an expimernt abot this and i wrote my report then i cheacked this again and forgot to look at the reviews and turns out i wrote a great report on the WRONG FACTS THANK YOU
@Jack: If you wrote that what hemisphere you are in does not affect the way water spins down the drain/toilet, than you wrote the correct facts.