During our visit to Quito Ecuador, we spent an afternoon visiting the equator and its adventures in physics. See how the water goes down the drain differently (circularly), even though the three basins are only about six feet apart.
Southern Hemisphere (above)
On the equator (below)
This proves the Coriolis effect that you've heard before. Right?
Are you now a true believer?
Don't be.
Apparently it's a trick.
The Coriolis forces can only kick in over long distances. Think hurricane.
The good folks at National Geographic tell us "Despite the popular urban legend, you cannot observe the Coriolis effect by watching a toilet flush or a swimming pool drain. The movement of fluids in these basins is dependent on manufacturer’s design (toilet) or outside forces such as a strong breeze or movement of swimmers (pool)." (Or in our video cases shown above, the water for the north and south examples wasn't perfectly still, as it was in the "test" performed directly on the line.)
Oh well. Don't you just hate a spoiler? Anyway, We enjoyed watching the sink drain. ;-)
For a full explanation, see Wikipedia here. And here's a summary:
"As the Earth turns around its axis, everything attached to it, including the atmosphere, turns with it (imperceptibly to our senses). An object that is moving without being dragged along with the surface rotation or atmosphere such as an object in ballistic flight or an independent air mass within the atmosphere, travels in a straight motion over the turning Earth. From our rotating perspective on the planet, the direction of motion of an object in ballistic flight changes as it moves, bending in the opposite direction to our actual motion. When viewed from a stationary point in space directly above the north pole, any land feature in the Northern Hemisphere turns anticlockwise—and, fixing our gaze on that location, any other location in that hemisphere rotates around it the same way. The traced ground path of a freely moving body in ballistic flight traveling from one point to another therefore bends the opposite way, clockwise, which is conventionally labeled as "right," where it will be if the direction of motion is considered "ahead," and "down" is defined naturally."
Here's more from the Wikipedia killjoys:
"Contrary to popular misconception, water rotation in home bathrooms under normal circumstances is not related to the Coriolis effect or to the rotation of the Earth, and no consistent difference in rotation direction between toilet drainage in the Northern and Southern Hemispheres can be observed.[49][50][51][52] The formation of a vortex over the plug hole may be explained by the conservation of angular momentum: The radius of rotation decreases as water approaches the plug hole, so the rate of rotation increases, for the same reason that an ice skater's rate of spin increases as they pull their arms in. Any rotation around the plug hole that is initially present accelerates as water moves inward."
Life was more fun in the days of a flat earth. ;-(
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