Why does water swirl when drained out of wash basin?
it has something to do with the pull of gravity towards the center of the earth. If you ever go south of the equator the water will go the opposite direction.
Has to do with the rotation of the earth. On the southern hemisphere it's suposed to turn the other way around than on the northern. But I have yet to see that with my own eyes...
It's the effects of inertia caused by the earth turning, in southern hemispheres the water swirls the other way, because the effects of inertia are opposite.
Coriolis does NOT affect it, by the way, that is an old myth: &The Coriolis force is so small, that it plays no role in determining the direction of rotation of a draining sink anymore than it does the direction of a spinning CD. The direction of rotation of a draining sink is determined by the way it was filled, or by vortices introduced while washing. The magnitude of these rotations may be small, but they are nevertheless gargantuan by comparison to the rotation of the Earth. I decided to include a picture of a draining sink, and the first one I tried in my house was found to drain clockwise (the opposite of what the silly assertions would have it do here in the northern hemisphere). This direction was determined entirely by the way the tap filled the sink. The direction of rotation of a draining toilet is determined by the way the water just under the rim is squirted into the bowl when it is flushed.& Hope this clears it up for you.
