why does the water down the plug hole allways swirl around the same direction?

Answer 1

A misconception in popular culture is that the Coriolis effect determines the direction in which bathtubs or toilets drain, such that water always drains in one direction in the Northern Hemisphere, and in the other direction in the Southern Hemisphere. This urban legend has been perpetuated by several television programs, including an episode of The Simpsons and The X-Files[1]. In addition, several science broadcasts and publications (including at least one college-level physics textbook) have made this incorrect statement.[2].

Many people who misunderstand the Coriolis effect compound their misunderstanding by claiming that drain water spins clockwise north of the equator and counterclockwise south of it, which is reversed from direction of spin that would result from the Coriolis force if it were a determining factor. In addition, the Coriolis effect is a few orders of magnitude smaller than various random influences on drain direction, such as the geometry of the sink, toilet, or tub, and the direction in which water was initially added to it. Most toilets flush in only one direction, because the toilet water flows into the bowl at an angle[2]. If water shot into the basin from the opposite direction, the water would spin in the opposite direction[3].

When the water is being drawn towards the drain, the radius with which it is spinning around it decreases, so its rate of rotation increases from the low background level to a noticeable spin in order to conserve its angular momentum (the same effect as ice skaters bringing their arms in to cause them to spin faster). As shown by Ascher Shapiro in a 1961 educational video (Vorticity, Part 1), this effect can indeed reveal the influence of the Coriolis force on drain direction, but only under carefully controlled laboratory conditions. In a large, circular, symmetrical container (ideally over 1m in diameter and conical), still water (whose motion is so little that over the course of a day, displacements are small compared to the size of the container) escaping through a very small hole, will drain in a cyclonic fashion: counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere—the same direction as the Earth rotates with respect to the corresponding pole.

Check out this link

Answer 2

There is an idea that it swirls in one direction in the Northern Hemisphere and the other in the Southern. This is said to be due to the Coriolis effect.

Some state that this is an urban myth and that if you try looking at a range of sinks/plug holes and use hot or cold water the result will not always be the same.

The New Scientist website has an interesting but very readable explanation (that it is not always in the same direction)

Answer 3

There is an effect called the Coriolis effect which is due to the fact that the earth spins around. On a large scale it can have an effect on weather systems. Hurricanes and tornadoes almost always spin anti-clockwise in the Northern hemisphere and clockwise in the Southern hemisphere.

It doesnt always do this, its also based on the way the sink is made, if there is a force applied to make it spin the other way. It was proven that although it does spin in only direction in each hemisphere it is possible for it to spin the other way, there just has to be momentum or force to do this. But naturally it is caused by the rotation of earth.

Answer 4

The rotation of the earth will cause the water to drain in a clockwise or anti-clockwise direction depending which hemisphere you are in. This effect is not very strong and can easily be counter acted on the small scale (unlike depicted in the Simpson's).
The earths spin also affects hurricanes and such in the same way but is not power-full enough to reverse the spin of a storm should it cross the equator.

Answer 5

Clockwise, Northern Hemisphere, Western Washington State.

Answer 6

Simple answer is that slight irregularities in your sink and its drain, or residual motion from the way the taps fill it, always make it go the same way.
I'll let others blether about the Coriolis force, as it's irrelevant to this question.

Answer 7

The swirl is due to the earth's spin. In the northern hemisphere it swirls in one direction, and in the southern hemisphere it swirls in the other direction.

Answer 8

Up here when you flush the toilet let's say. It spins clockwise, In Australia in spins counterclockwise. It has to do with the magnectic forces of our planet,

Answer 9

Well, it doesn't. In the southern hemisphere, it swirls the opposite direction.

Answer 10

it doesn't if you check it out sometimes it goes the other way, it depends on which hand you use to pull the plug