Now as every eighth grader in New York State knows, our toliets go counterclockwise, and everyone below the Equator their toliets go clockwise. What happens if you place a toliet directly on the Equator? Which way does it go? For the sake of this question, the toliet is placed exactly on the equator, so saying it would follow the rules for whichever pole is closer will not work.
Most eigth graders in NY who can log on to this site know it’s not true.http://www.straightdope.com/classics/a1_161.html
sigh
The Coriolis Effect
They lied to me, I swear. The New York State Regents Board is sham. I can’t believe one of my favorite teachers has been spewing ignorance. A sad day in the history of my education.
It’s okay, man. We all have this happen-the first time we realize Teachers Spread Urban Legends.
You’ll get through it, man. We’re here for ya.
On the contrary, you just learned a very valuable lesson: don’t trust everything your teachers say.
I read that article (after visiting Snopes) and I still am a bit confused.
[quote]
On the other hand, if Shapiro pulled the plug after waiting a full 24 hours, the draining water spiraled counterclockwise, indicating that the motion from filling had subsided enough for the Coriolis effect to take over. When the plug was pulled after four to five hours, the water started draining clockwise, then gradually slowed down and finally started swirling in the opposite direction[/qoute]
Doesn’t this mean that the CE is effective? Does it actually mean that the loo will flush the same direction in either hemisphere?
My freshman college physics teacher told me that glass in windows in old buildings is thicker because the glass has flowed.
Shapiro showed that the CE can indeed apparently have a measurable effect on a tank of water. It’s just that outside of a carefully controlled experiment in a physics lab, it’s completely overwhemed by larger, local, accidental effects. Unless you go to the sorts of lengths he did before flushing your loo - and provided your childhood toilet training wasn’t uniquely weird, I suspect you don’t - then the CE is completely irrelevant in the everyday situation.
I may as well mention that I’ve read both Shapiro’s paper and the later one by a team in the southern hemisphere, in Sydney I believe, who repeated the experiment to check that you get the opposite rotation there under similarly careful conditions. An officemate (with a Ph.D. and all) had turned out to be vectoring the myth to his undergraduate astronomy class, so I felt I had to give him the straight dope on the matter and dug the papers out of the library.
Neither is little more than a short note, so they don’t go into most of the details. But the thing that bothered me was the niggling doubt that they’d proceeded by controlling successive bigger effects until the CE was dominant. Yet how did they know it was the CE effect and not some other residual bias ? This is a problem experimentalists always face, but usually you’re trying to test a detailed prediction. Here it’s effectively an either/or, so there’s no cross-check.
Yes, Shapiro was plausibly seeing the Coriolis effect in action, but I’m not quite sure he proved he did. What he certainly showed is that it’s hard to see anything that might be it using bodies of water smaller than an ocean. And that’s enough to refute the myth.
Well, either that or just check a few different types of toilet and see if they agree. They won’t.
As you’ve no doubt already surmised, the magnitude of the CE drops to zero at the equator, so no matter how careful your experiment, you won’t see a pattern to the way the water swirls.
I always made a point of debunking that one when I taught chemistry.
It never fails to amaze me how some teachers/professors can continue to spew the same baseless anecdotes year after year without ever feeling the need to verify the veracity of said anecdotes.
Hey, I need to add “slow flowing glass” to my list!
Misconceptions spread by grade-school textbooks
I know that some teachers propagate it, but has anyone seen the “CCW Toilet” error in an actual text?
What I find confusing about the Coriolis Effect is the following paradox:
The coriolis effect causes objects in the northern hemisphere to be diverted to the right, thus causing a swinging pendulum to move in a clockwise fashion. However, it causes hurricanes (and maybe tornadoes and whir? I’m not sure) to swirl in a counter-clockwise direction. If you draw a picture of a line and divert it to the right, this certainly isn’t what you’d expect! What’s the explanation?
“whir” = whirlpools, above :smack:
According to Cecil, it looks like this issue is very similar to the Coriolis Effect, in that the principle that it is based on is true, but the real-life effect is not as it is often taught. Glass actually will flow, but it takes millions of years to do it, so the effect is negligible.
I have a low post count for a reason: people here on the boards tend to cover things very nicely and I try to eschew the “me too” kind of post. That being said: toilets don’t qualify for the Coriolis Effect experiment. The water frp, the tank is directed to swirl by the inclination of the vents leading into the bowl. It does make me want to cast up a toilet with vents pointing in the other direction, though. I could tell my friends I bought it down-under.
I have done two experiments with Coriolis Forces, however. I can tell you that a big swimming pool is large enough to exhibit the CE. I put a trash pump in the deep end of a 40,000 gallon pool that had lain quiescent for 200 days, undistrubed. The pump was activated and in an hour or so a very slow counter-clockwise vortex was observed above the pump inlet.
Being the outdoor physicist that I am at times I took a pool skiimer net and stirred clock-wise around the vorticular area for several minutes until a clock-wise vortex was effectively feeding the pump inlet.
I then read my current copy of Nature for an hour or two (actually I went into town for lunch) and when I returned the counter-clockwise rotation had been re-established!
I post with tongue in cheek at least for style. I have done this experiment twice and pools are big enough to exhibit appreciable CE forces. More info if needed.
It’s possible, though, that CCW flow patterns might be established at the inlet to the pump due to the action of the pump itself, particularly if the inlet length is relatively short and it’s a centrifugal pump. I could easily see this as being the dominant effect in creating a vortex, far overwhelming the Coriolis Forces (although I admit I don’t have a good intuitive feel for order of magnitude of either). As bonzer said, it’s hard to be sure its Coriolis you’re seeing, and not some other residual force.
If you put a low pressure spot on the earth, wind will flow into it. If then it turns to the right it will be going anticlockwise. I don’t know if this is the reason, but it could be.
I should have been more specific. The inlet to the pump was the only thing in the pool. The pump itself was pulling through a fifteen foot hose so I don’t think there was a lot of feedback to the body of water. I calculated the difference in rotational speed from the difference in latitude at either end of the pool and over the course of several hours the deflection adds up to several feet. I think that’s enough to induce a true CE effect. Should I publish? 
If you had a big enough bathtub on the equator, maybe you’d get vortexes in opposite directions in different halves (provided it was left to stand long enough that the coriolis force predominated)