Balancing an Egg on the Equator...

[Beady]

...whirlpools in the toilet, you know the kind of thing. I need a quick and simple reference, that uses words of as few syllables as possible, for these phenomena.

I got into a discussion on a travel show forum (Passport to Latin America), where the host showed one of those whirlpool demonstrations on the equator. Then a forumite from Quito chimed in with "eyewitness testimony" about whirlpools and eggs. The forum is a fan site more than a place for serious discussion and most of the participants have about as much substance as cotton candy; they need delicate handling and easily-understood explanations (and a very polite presentation if I'm not to drive them away).

Seems to me there was a book called something like "A Tornado in Your Toilet," but Amazon is no help at all.

[SomeGuy]

Google: corioli

[Beady]

I tried that, already. I said, "a quick and simple reference, that uses words of as few syllables as possible," and, "most of the participants have about as much substance as cotton candy."

I doubt I'll get through, but I'd still like to try.

[Dragon]

Try the Snopes (http://www.snopes.com/science/coriolis.asp) entry.

In a nutshell the Coriolis Effect is very weak when it comes to things the scale of eggs and drains. You might get it to work in lab conditions, but not in a couple of scruffy sinks placed either side of the equator to impress the tourists. The direction of rotation there would be due to the shape of the sink/plughole/waste.

[tkingdoll]

yeah, as Dragon says it's pretty much in the myth corner. You can get your bath water to drain in any direction you please.

[SomeGuy]

yeah, as Dragon says it's pretty much in the myth corner. You can get your bath water to drain in any direction you please.

You must have a bath with a lot less imperfections than mine, because mine certainly only drains in one direction.

[Dragon]

You must have a bath with a lot less imperfections than mine, because mine certainly only drains in one direction.Clockwise or anti-clockwise? Northern or southern hemisphere?

[SomeGuy]

Counter clockwise, northern hemisphere

[Dragon]

- which is the "correct" direction, of course. :D

[SomeGuy]

- which is the "correct" direction, of course. :D

Yeah I've got my bath properly trained!

However downstairs I have 2 sinks, and only one of them seems to realize he's on the northern hemisphere.

[tkingdoll]

You must have a bath with a lot less imperfections than mine, because mine certainly only drains in one direction.

No, I said you can get the water to drain any way you want. That's not the same as it naturally going one way or the other because you have a specific bath.

I just realised I've never checked mine. I think I will.

[Deetee]

Can I volunteer to do it for you?

[Michael C]

The whirlpool demonstration can be done anywhere. It would be a good trick in a "debunking" lecture (has Randi ever done this?). There are simple ways of imparting a clockwise or anti-clockwise rotation to the water in the basin: for instance, just turning to face your audience will do the trick. You just have to remember which way to turn. It helps if the basin is not circular. See: http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html

If you want really quick and simple references, the Straight Dope com is a good place to look. See http://www.straightdope.com/classics/a1_161.html for draining bathtubs and http://www.straightdope.com/classics/a2_089.html for balancing eggs.

[Beady]

Ah! Snopes and Cecil Adams! Thanks, gang, exactly what was needed.

[Dragon]

Just did a quick experiment in the little sink in my basement loo.
Result: Direction of the whirlpool dependent on initial rotation of the water.

Beady - why not ask your cotton candy friends to experiment for themselves?

eta

As you know, The Way of the Woo is such that personal experience trumps all else.

[Beady]

Beady - why not ask your cotton candy friends to experiment for themselves?

I'm planning to, but I want to get a little authority behind me, first. Remember, I now have to contend with "personal experience" by the guy from Quito.

Arguing from authority is supposed to be a no-no, but I figure I have to do something to lift my position out of the realm of personal opinion before they'll be motivated to experiment.

[Lisa Simpson]

My son has balanced an egg on its end and do not live at the equator. He did it on a non-equinox day as well. Just takes a little practice and a steady hand.

[Dragon]

Ah - Quito - I blame the lack of oxygen.

Arguing from authority is not necessarily fallacious - anyway you have the science to back you up.

Good luck and keep us posted!

[wollery]

Can I volunteer to do it for you?Should have volunteered to do it with her! :p

[In My Spare Time]

http://www.badastronomy.com/bad/misc/egg_spin.html
http://www.badastronomy.com/bad/misc/coriolis.html
Couple of easy reads on the subjects from the Bad Astronomer

[JoeTheJuggler]

I'm planning to, but I want to get a little authority behind me, first. Remember, I now have to contend with "personal experience" by the guy from Quito.

Arguing from authority is supposed to be a no-no, but I figure I have to do something to lift my position out of the realm of personal opinion before they'll be motivated to experiment.

My own personal experience:

I lived in Quito for two years and did pay attention. I lived just barely south of the equator, and drains spun in either direction depending on the shape of the basin and the direction of water jetting in--same as here in the northern hemisphere.

There's a toilet at a place I work frequently (about 38 degrees N. Latitude) where the water doesn't spin at all. It's got really hard jets of water pointing down, and the sides of the basin are especially steep. The water just goes straight down.

The coriolis force is too weak by several orders of magnitude to have any effect.

[JoeTheJuggler]

As far as balancing an egg: just put a few grains of salt underneath the table cloth, and it's easy enough.

[JoeTheJuggler]

My son has balanced an egg on its end and do not live at the equator. He did it on a non-equinox day as well. Just takes a little practice and a steady hand.

On a bit of a tangent: I have a friend who does traditional Japanese top spinning ("koma" I think it's called). He's also a retired engineer, so he's always playing with different materials and such. He machined out a metal top with a relatively heavy flywheel. The shaft was about 3 mm wide, but didn't come to a point--instead it was flat with about a 0.5 mm diameter surface. He had a piece of glass (it was a lid to one of those pyrex bakeware dishes) and challenged us to balance the top on the glass. No one could do it. It really felt impossible.

Then he spun the top and put in on the glass. Naturally it spun for a long time since there was so little friction between the two materials and a big heavy flywheel. So it sat on a table while we ignored it. After around 30 or 40 minutes, it still wasn't precessing as I would have expected. In fact, when we looked closer, we could see it had stopped spinning and was standing still perfectly balanced.

[Beady]

Good luck and keep us posted!

Turns out my biggest opponent is a teacher(!) who just wants to gush at the host. It seems that science is something separate from a travel show, and I'm ruining it for her. I managed to work in pointers to snopes, JREF, the straight dope and bad astronomy, then I yielded to my baser instincts and let her have it:

"...and there's no need for you to be so testy; this is not *your* forum, after all. It's a place to talk about what was on the show, and I'm talking about what was on the show. Besides, if you really are a teacher, I'm surprised you don't think education is something constructive [she told me to find something constructive to do with my time]. I saw what used to be called a "teachable moment" and took the opportunity. Why didn't you do the same? I'm also surprised that, as a teacher, you apparently consider "science" as something to be segregated from other topics."

I'll probably either be banned or edited, but what the hell.

[karener]

The coriolis "force" isn't actually a real force but comes into play with fluid moving over the rotating earth - and can only be seen in processes with longer time scales. So, your ocean currents and even hurricanes may have some influence from the coriolis force, but shorter time scale processes such as toilets or baths draining and even tornados will not.

[skeptigirl]

As far as balancing an egg: just put a few grains of salt underneath the table cloth, and it's easy enough.No equinox, equator, salt or table cloth needed, just patience.

http://ucsu.colorado.edu/~lambd/images/eggs.jpg

[skeptigirl]

The Moon looks upside down when you change hemispheres. :D

[Schneibster]

The coriolis "force" isn't actually a real force but comes into play with fluid moving over the rotating earth - and can only be seen in processes with longer time scales. So, your ocean currents and even hurricanes may have some influence from the coriolis force, but shorter time scale processes such as toilets or baths draining and even tornados will not.Actually... :D

Turns out that you have to allow for coriolis force when figuring the trajectories of long-range artillery. That only takes three minutes to get to its target, but it's long enough.

[skeptigirl]

So is it coriolis, Schne or the fact the Earth is turning? Because one depends on air and water moving at different speeds. Is one side of the missile moving faster than the other side?

[JoeTheJuggler]

No equinox, equator, salt or table cloth needed, just patience.

Here's a challenge for you. Can you shell a raw egg without breaking the membrane? I've heard that this is possible to someone with a steady hand and plenty of patience.

By the way, this fits in with this thread's topic because it's another example of something unaffected by the Coriolis force that works the same north or south of the equator. :D

[Schneibster]

So is it coriolis, Schne or the fact the Earth is turning? Because one depends on air and water moving at different speeds. Is one side of the missile moving faster than the other side?Coriolis is the fact the Earth is turning. It's a pseudo-force, apparent only to one who participates in circular motion of one kind or another. Imagine if you were standing at the outside of a big merry-go-round, and threw a ball at the center. What would you see? Now imagine you can't tell the merry-go-round is turning.

[skeptigirl]

I see. (http://en.wikipedia.org/wiki/Coriolis_effect) I had been under the wrong impression it had to do with currents and the fact variable speeds within the currents flowing E-W or W-E caused the spin.

[skeptigirl]

Here's a challenge for you. Can you shell a raw egg without breaking the membrane? I've heard that this is possible to someone with a steady hand and plenty of patience.

By the way, this fits in with this thread's topic because it's another example of something unaffected by the Coriolis force that works the same north or south of the equator. :DNot that I have that kind of time to waste with all the time I manage to waste in these forums. On occasion however, when cracking an egg, the shell but not the membrane breaks. So I don't think it would be that hard.

[Cuddles]

I was going to ask who the hell spends their time trying to balance eggs, but apparently Skeptigirl has already answered that one... :p