Does Water Swirl the Other Way in the Southern Hemisphere?

The definitive answer about the direction water swirls in two hemispheres

For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time.

The idea that water going down a drain or flushed down a toilet swirls in opposite directions in the Northern and Southern Hemispheres has a long history. But few have ever done the experiment. Destin from Smarter Every Day and I performed identical experiments in the Northern and Southern hemispheres. What we found is the direction of water swirl in a toilet, sink, or bathtub is determined by other sources of angular momentum. However if the body of water is big enough, e.g. a kiddy pool, and left still for long enough (at least 24 hours), then the Coriolis effect is observable with water swirling counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere.

Gordon McGladdery did all of the sound design for the video. We used two songs from other artists (licensed of course). Derek split the first one up so it fades from video to video, and Gordon split the instruments up on the second one. There are violins on one video and percussion on the other for example. It's really neat.

MORE INFO:

This site is a great resource on the Coriolis effect and ways people have gotten it wrong:

[smartereveryday]

One of the most awesome projects I've ever had the opportunity to be a part of. Derek made it happen!

[WoodByWright]

still one of my all time favorite colabs!

[anepicotter]

The structure of these videos so they work best when played simultaneously is actually awesome! I never watched either of them but watching this is just so cool how you take turns speaking and the video is set up so that there's always something to be looking at- it's just so immersive I feel like I don't have even a second of idle thoughts before something else happens but it's also not like it's an overwhelming onslaught of information. It's just so we'll made to keep the attention of the viewer

[unvergebeneid]

At the time I hadn't noticed that Destin, living in an imperial country, used metric units and Derek, living in a metric country, used imperial units.

[kyknmk]

the way how the guy on the left is so close to the toilet when it flushes makes me extremely uncomfortable

[MysticDonBlair]

Birds fly upside down in the southern hemisphere.

[vincentrobinette]

I served a mission for my church in Brazil. One of the first things I tried, was fill a sink with water, let it sit over night, then pulled the drain plug with a string, rather than reaching in. It indeed swirled clockwise. I tried it several times with a sink behind the house, that is normally used for washing cloths. It too drained clockwise. The toilets were no indicator, since the offset jets determined the direction of the vortex when flushed. I was in Minas Gerais, which is far enough south, to make it pretty reliable as long as the water had time to completely stagnate. I even placed a board over the outside sink, to make sure no wind could disturb the water. If you drained the sink immediately after use, any turbulence in the water would override the effect, and it would swirl in either direction, It didn't take much, to influence it.

[Jack-dotq]

1:50 why did the American say meter and the Australian say feet 😂😂😂

[LionTheCheetahChaser]

It's interesting to note that at the level of a tornado, which is considerably bigger than a bathtub but still pretty small on the scale of the Earth, about 95-98% are said to rotate cyclonically (counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere), but there is that small fraction of anti-cyclonic tornadoes.

[AbhilekhPandey]

Lives in us: 1.5 M
Lives in Austalia: 5 foot

lul

[thatjokerperson]

legend has it flat earthers can make up a reason for this

[CNCmachiningisfun]

And with that, the flat earth 'theory' goes down the drain :) .

[TheeZack]

Hey can I copy your homework?

Sure, just change it a little so no one notices.

[LiborTinka]

You might get more consistent results with a very long pendulum (Foucalt's pendulum), but that would be more expensive to constructs. There is one in my city and it is built into a tower so it is shielded from weather. The pendulum swing is steadily altered by the Coriolis force, which can be observed by a pattern drawn by a stream of sand coming from the pendulum weigh.

[albundy]

Once again, we've learned something, thanks to the Simpsons.

[BurazSC]

the world need more videos like this...scientists in the bath and on the toilet.

[realallthings]

Southern hemisphere : we do clockwise motion

Northern hemisphere : we do anti-clockwise motion



Equator : I miss the part where that's my problem

[gendaattila]

I think the geometry of the drain can also create vorticity, as in case of the wings of an airplane, the no-slip boundary condition on the surface of the wings is a source of vorticity even in previously irrotational velocity fields (see for example the Kutta condition). What I mean is if you have a drain formed as a Kaplan turbine for instance, even if the turbine is standing, the flow will begin to rotate automatically and that is not becouse of the Coriolis force.

[ryanbarr]

I once cut the base off a 5 gallon drum, wrapped copper wire around the neck and hooked it to a car battery. When I switched it to positive it increased the up the spin rotation and when I hooked it up to negative it just went straight down. I don’t remember how well I controlled the experiment to not have any motion in the water prior to pulling the plug. However, the effect that the positive and negative electric current had was repeatable.

[leviteau]

Don't know how I didn't see this 4 years ago, but thanks Youtube recommend, you were actually helpful for once