emptying a water bucket through a small hole at its bottom causes an anticlockwise whirl in water always, why?

Question

When water is drained from a tank through a drain hole, the whirl developed on the water surface spins in the anticlockwise direction always in any where in India. But my friend in Australia is arguing with me that it is in clockwise direction always. which one is correct?

Answer 1

Good grief. Four answerers and the original asker have all bought into a proven urban legend.

IT ISN'T TRUE PEOPLE.

Water will go down either way no matter where you are.

The twisting effect of the Coriolis force is real and does influence certain large things like the movement of air masses, but the effect is so small that it plays no role in determining the direction in which water rotates as it exits from a draining sink or toilet. The Coriolis effect produces a measurable effect over huge distances and long periods of time, neither of which applies to your bathroom. Toilets and sinks drain in the directions they do because of the way water is directed into them or pulled from them. If water enters in a swirling motion (as it does when a toilet is flushed, for example), the water will exit in that same swirling pattern; as well, most basins have irregular surfaces and are not perfectly level, factors which influence the direction in which water spirals down their drains. The configuration of taps and drains is responsible for the direction of spin given to water draining from sinks and bathtubs to a degree that overwhelms the slight influence of the Coriolis force.

The belief that the Coriolis force influences the direction in which water drains from plumbing fixtures is widespread and has been repeated as fact in a number of venues, including popular television shows (such as world traveler Michael Palin's Pole to Pole) and even in textbooks. We can only speculate on why people are so enamored of this snippet of misinformation, guessing that it has something to do with the desire to find some of the mysteries of science in the realm of the everyday.

Answer 2

This is not true. there are certain forces in the northern and southern hemisphere that influence the direction, but the amount of water needed for this is way too big for the "sink" experiment. this is only a very well distributed and repeated rumour. It does happen in cyclones and hurrianes, however.
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Try this: block the sink with a plug and swirl the water clockwise with a spoon. let the water stop and unplug. the water will most probably rotato clockwise, because the TINY remaining momentum is still larger than the force due to the earth's movement.
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Cheers.

Answer 3

It is called the coriolis force, yet it is not a true force. it is natures way of counter balancing the roation of the earth, by rotatin the fluid in the opposite direction, and yes it is hemisphere dependent, chaning directions from north to south. logically this means dead center of the equator, the should be no rotation, but this is only a guess, never read up if this actually happens at the center of the equator. another topic of interest related to the coriolis force is Focaults Pendulum, here is a wikipedia link:

http://en.wikipedia.org/wiki/Foucault_pendulum

Answer 4

The direction of the spin is caused by the earth rotation. If you are north of the equator (India), it will always be anticlockwise, if you are south of the equator (australia) it will always be clockwise. so you both are correct.

Answer 5

The reason is the Coriolis Force. India is in the Northern hemisphere, and Australia, in the Southern. The Force and it's effect vary either side of the equator. It is explained in detail at http://www.discovery.com/area/skinnyon/skinnyon970523/skinny1.html

Answer 6

It is caused by the rotation of the Earth. So the direction depends upon your location relative to the equator. India is north of the equator, and australia is south.

Answer 7

The Coriolis Affect only applies to the rotation of storms, or anything else that is large enough to be affect! Sinks, toilets, and buckets are way to small for this to be a factor!

Answer 8

The direction it spins is determined by which hemisphere you live in.

I wonder which direction it would spin if you were dead centre of the equator.

Answer 9

I do believe both are correct and it has to do with the location above or below the equator. Is due to Earth's gravitational pull is my guess.

Answer 10

both are correct, northern and southern hemispheres rotate it opposite directions