原创 The truth about toilet swirl unravelled!

I don’t know about you, but I always enjoy seeing something new, so today started off with a bang when I received an email from my chum Rick Curl saying: "What’s interesting about this is not so much the material being presented, but the method they chose to present it."

This somewhat cryptic message was accompanied by two links:

https://youtu.be/aDorTBEhEtk

https://youtu.be/ihv4f7VMeJw

In turn, these links were augmented with the following instruction: "You MUST open the two links in two different browsers -- not two tabs in one browser."

"What could this possibly be about?" I wondered, but I'm always "game for a laugh," so I did as I was instructed.

This really is rather cool. I'm sure that as kids we all heard that water spirals anticlockwise when exiting a sink, bath, or toilet in the Northern hemisphere and clockwise in the Southern hemisphere. This is due to the Coriolis Effect, which results in a deflection of moving objects when the motion is described relative to a rotating reference frame.

The problem is that when one actually tries to observe this for oneself (and haven’t we all done so?), the water doesn’t seem to want to follow the rules. Take the following image of a dual sink, for example. Although it's hard to make out here (you can see it in one of the videos mentioned above), the water in the left-hand sink is spiraling anticlockwise, while the water in the right-hand sink is spiraling clockwise. Even worse, the narrator notes that the water sometimes drains one way and sometimes the other way.

I think it's fair to say that we all eventually come to the conclusion that the way in which the water exits is predominantly driven by the design of the artifact in question, and that the Coriolis effect is too slight to make itself apparent in these small-scale test cases. So I'm well-impressed by the two guys in these videos who determined to provide a brilliant example of the effect in action.

As Rick noted, you have to open each video in a separate browser and have the two videos running side-by-side (the videos include "5-4-3-2-1" images at the beginning to facilitate your syncing them up).

Of particular interest to me is the fact that the Northern hemisphere video was captured where I currently hang my hat here in Huntsville, Alabama, USA. I wish I'd known it was taking place, because I would love to have been there to see it happen.

I think that these videos would be great for teachers to show kids at school; don’t you? Have you seen any other videos like this that manage to be highly educational and fun at the same time?