What is the direction of water swirl when plug from wash basin is pulled out?

Answer 1

It depends primarily on the geometry of the sink.
Under ideal conditions it probably would be anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere due to the Coriolis effect, but the geometry of the sink is a significantly more powerful factor than the Coriolis effect.

Answer 2

"rockymtns2" is correct, and has the best answer of the 6 answers before mine. The Coriolus Effect applies only to very large fluid masses, typically those that are hundreds of miles in diameter, such as ocean basins and hurricanes. So when you pull the plug from a wash basin, the direction of the drainage swirl, if one develops at all, is essentially random. If the basin itself is symmetric, then the greatest factor affecting the direction of the swirl is the collection of random currents that you set up by pulling out the plug.

If you understand how the Coriolus Effect works, then you will understand why it cannot affect a small fluid mass such as a tub of water. The earth rotates on its axis once every 24 hours. The circumference of the earth is about 25,000 miles. So an object at the equator is traveling in a circle around the center of the earth at approximately 1000 miles an hour. However, at locations other than the equator, the circle of travel is smaller, and therefore the speed is lower.

In a large fluid mass, such as the ocean or the atmosphere, some of the fluid may drift northward or southward. But as it drifts, it maintains its original speed, at least for awhile. So if the fluid drifts towards the equator, then soon it will be travelling slower than the earth beneath it, and will lag behind, arcing towards the west. If the fluid drifts away from the equator, then soon it will be traveling faster then the earth beneath it, and will move ahead, arcing towards the east. This combination of arcs sets up a clockwise circulation in the northern hemisphere, and a counter-clockwise circulation in the southern hemisphere.

But in a wash basin, toilet, or swimming pool, the north and south boundaries are too close together to create a Coriolus Effect. The north lip of the basin and the south lip of the basin are traveling around the earth at exactly the same speed, by any reasonable measure of precision. So no Coriolus Effect occurs. If there *was* a Coriolus Effect, then you would not have to pull the plug to see it -- the water would start to rotate in the basin long before you ever pulled the plug!

Answer 3

The flow of water down drains has nothing to do with which hemisphere you are in (like we're all led to believe); the Coriolis effect is much too small. It will be determined by random motions in the water (or, in the case of toilets, by the direction of the incoming water). Experiments have been done which show that the water will indeed drain in opposite directions in the northern and southern hemispheres if you are careful enough to eliminate all motion in the water first; this is very difficult to do, and will not happen by itself (it also requires perfectly symmetric containers).

Answer 4

I stay in Michigan (the only shaped like a mitten) interior the USA interior the Northern Hemisphere. The water swirls clockwise basically like it does in all the NH. it fairly is the rigidity of the Coriolis. I laughed at "anti clockwise". we are saying counter clockwise.

Answer 5

always anti clock wise

imagine a bathtub on a plane you pull the plug and go to australia ,does everybody think that when you cross the equator it changes direction

rediculous ,

because of the direction we turn around the sun
every thing follows,


vines all over the world wind them selves anti clockwise around the trees
winds,ocean currents ,weather patterns ,the way the spirals in our bones devellop,the spiralling devellopment of branches on trees,the direction of the spiraling action of tornados ,spirals in rivers ,etc

i have seen vines all over the world ,and all go in the same direction ,if you change it they contort and reverse to the original position.

Answer 6

It's counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

Answer 7

It depens on where you are in the world. in the northern hemisphere it will run out clockwise and in the southern hemisphere it willrun out anti clockwise.

Answer 8

see rockymtns2 for the correct answer

ignore these other fools who don't what the coriolis effect/force is and who watch too much Simpsons

Answer 9

http://en.wikipedia.org/wiki/Coriolis_effect#Draining_bathtubs.2Ftoilets