Why does water funnel

Even in a tub having a perfectly symmetric drain, the circulation direction will be primarily influenced by any residual currents in the bathtub left over from the time when it was filled. It can take more than a day for such residual currents to subside completely. If all extraneous influences including air currents can be reduced below a certain level, one apparently can observe that drains do consistently drain in different directions in the two hemispheres.

Finally, Thomas Humphrey, a senior scientist at the San Francisco Exploratorium, discusses in more detail the reasons why we do not see the Coriolis effect at work in the bathroom:. For a fee, they will allegedly demonstrate that the toilets flush in opposite directions. It is only for show, however; there is no real effect. Yes, there is such a thing as the Coriolis effect, but it is not enough to dominate the flushing of a toilet--and the effect is weakest at the equator.

Coriolis acceleration at mid-latitudes is about one ten-millionth the acceleration of gravity. Because it is a very small acceleration, it needs a very long distance for it to produce an appreciable curvature--and hence directionality--to the motion. A toilet or sink is just not large enough. The Coriolis effect influences because wind velocities may be hundreds of times greater than the motions in a sink and because the distances involved are far larger than the tiny draining diameter in a sink or toilet.

The net motion in the water becomes much more pronounced as the water is forced to move in toward the center of evacuation, causing the normally invisible flows in the water to become visible as the water nears the drain. The ultimate direction of that flow is random--it can go one way one time, the other way the next. Objects not attached to the surface of the earth water in a sink going down a drain will create a vortex going the opposite direction.

So in the Northern hemisphere, it moves clockwise. In the Southern hemisphere, it moves counter clockwise. On the equator, water goes straight down.

It isn't alway that simple since the earth is not a perfect sphere, but that is the general idea. This is a basic explanation of the Coriolis Effect. There are several different experiments you can do to see the effect many are in video form on the internet. Calvin Roberts, Detroit. US The Coriolis acceleration definitely has an effect - how large it is, I am not sure, but the longer it takes to drain, the larger the effect. You have water going down toward the center of the Earth, and the Earth spinning around the North Pole.

The "cross product" of velocity with spin gives the Coriolis acceleration. This is an acceleration, so it would take time to build up, and cannot overcome preexisting powerful momentum opposing it before the water exits via the drain, i. Reid, Huntsville, AL USA Please tell me that all or most of the people that have added their 5 cents worth to the above are under 5 years old.

If not, there is a major blockage in education in you area! Clash, Dunston, UK" I mean really, are you living on the surface of the earth or inside? I can confirm that playing snooker in Australia is the same as playing in the UK; the balls don't curve in different directions.

Do you drink snooker balls? Ever heard of Liquid, solid and gas? Guess which one water is. And by the way, if it is a scientific fact, then please show me to the uneducated, brainless scientist that proved that one! John Walker, Derby, UK" And you John, so you are saying that people in the South look at their watches from the back and in the North from the front, or vise verse or are you saying that watches turn the opposite way in the North and South? What a retarded experiment!!!

Everything that is measured on the earth is taken from the surface, looking at the surface and is measured for that particular area, not from above and below. Kirsty , Leeds, England" Kirsty girl, please don't become something that has anything to do with science or physics. Maybe think on the lines of I don't know, housewife? Just e3liminate the problem of sink and plug hole issues and just pour the water people!!

No one said anything about what happened to the water at the poles. I came into some money and, having nothing better to do, I took a cruise to Antartcia and managed to catch a ride to a camp very close to the South pole. I took along a flat wash basin that had a hole and a rubber plug in it. I filled it about half full and took it outside so it would not be influenced by structural or gravitational fields of the buildings.

I carefully pulled the plug and watched. Unfortunately the water froze before it could drain out so I guess this is why the effect is only seen at or near the equator. Land Waylamd, Chino. California ISA When you get drunk which way the room is spinning? Seriously now, I think the water is just random, but is true for the tornados. The north hemisphere the tornados are spinning counter clockwise and on south hemisphere the tornados are turning clockwise.

Dan the man, Bucharest Romania Unbelievable. The vortex only occurs when the water level is low so should in effect do the same to your half finished cup of tea. It doesn't because the force while exists is not strong enough. People have talked of physics and shapes of bowl etc but nobody mentioned the real force of the waste pipe.

Unromantic as it may be the swirl of a plug hole is simply due to the way the waste pipe is configured explaining the phonomenem of hand swirled sinks turning the other way. When you empty a bath there is no vortex as the pipe is full due to the pressure of the water. Only when the pressure reduces due to the volume of water does a swirl appear the direction of which depends on the shape of the pipe below.

Think not what you are told but what is physically happening otherwise you will end up stood on the equator listening to a charlatan with a bucket. The effect of draining amplifies small movement as the water moves to the centre the same way a ballet dancer increases spin speed by putting arms in. Any chaotic system can be influenced by tiny changes, The butterfly effect. Other effects such as basin shape may be larger but over a large number of tests on different set ups random factors should cancel out leaving any small consistant factor to show a measurable majority, or of course the most popular basin design could tip the balance.

Steve Turner, Witham, Essex I have spent the last 15 years exploring this phenomena on a full time basis and I can now give the definitive answer. Ideally one should consume a kebab prior to urination. I hope this answers the question once and for all. Baz l'hommedeleau, London UK Wow people, just wow. Some answers are way out there. Others are so convoluted that it's beyond reasoning. Only one person has come close to a logical answer to the apparent 'different' direction.

Simple answer, the direction is the same, it's only the viewers point of observation that changes. Anti-clockwise spin when viewed from the southern hemisphere, appears as a clockwise spin when viewed from the northern hemisphere. And guess what, vice versa applies regardless of the spin direction.

Think about it, devise a simple test for yourself using you eyeline as the 'equator', test it for yourself, and prove to yourself it's simply your view perspective that 'changes' the direction, not the direction of spin suddenly stopping at the equator, and then miraculously reversing itself. Paul Nankervis, Perth Australia I've studied this with many different tubs, kitchen sinks, bathroom sinks for many many hours with over a hundred tests and I concluded that what hemisphere you're in has nothing to do with the direction of the spin.

Joe Vortex, Montreal, Canada This is a common myth, and the previous comments settle it quite well. I only wish to add that the size or distance needed for Coriolis to have an noticeable effect is 10kms Natassia Day, Perth, Australia Having read most of the above I am thinking of how to exploit this feature.

My current interest is in making, as a hobby, a water wheel electric power generator. There are of course hundreds of examples, the one that interests me is a backpack model, a tube to be inserted into a flow of water and to produce campsite lighting.

My version could be called the Downunder increasing pitch screw turbine. The downunder because I am in the southern hemisphere and of course the water flows opposite that of the northern types, it looks like that idea is a no go. The whole thing, alternator and all about 3 ft long and 6 inches in diameter, it would be contained with ropes tied to trees, rocks, a bridge or whatever.

I then went immediately upstairs and flushed that toilet and it went clockwise. My downstairs and upstairs are in the same hemisphere.

Why did they not rotate in the same direction? Why doesn't the bath water spin increasingly fast in the first place if left to sit for days? I'm with the "Definitely has an effect, but it's probably of mathematically insignificant magnitude when compared to 'other' factors.

Unless you happen to be a ocean sized lump of atmosphere with nothing else better to do" side. Coriolis force is in effect with this phenomenon.

Under strict lab environment, it is always counterclockwise in the northern hemisphere. As a matter of fact, in a random household environment, a high percentage of the results is counterclockwise in the northern hemisphere. But due to other forces such as sink design, initial spin, there are some cases where a small percentage go wrong. So basins were just 2 standard sizes, facilitating a controlled experiment. In 5 of the 7 basins I tested, the direction was anti-c, in the other 2, clockwise.

That would strongly support the 'random' opinion, except for the fact that I tested each basin three times, getting the same result on all replications. I feel this reduces the 'random' case. Btw, lets not make ad hominem comments in our discussions.

It is an inertial force caused by the rotation of an object. It is not imaginary or fictional , but is very real in the rotating reference frame. The Coriolis force tends to make things on the surface of the object to spiral a certain direction.

As the earth rotates, this motion causes everything on the surface to experience the Coriolis force, including the water in your sink. A: You might have heard that this has something to do with the Coriolis effect. This force has noticeable effects only on long-lasting motions and large bodies like oceans and large atmospheric phenomena such as hurricanes. The Coriolis force is much too weak to have any effect on short-lived phenomenon in small basins of water under normal conditions.

Before opening the drain, the water already has some motion, although it might be too slow for you to notice. As the water moves toward the drain, its rotational motion gets amplified, i. Students can easily confirm that the water ends up swirling down the drain in the same direction that it was originally moving. They start this investigation by filling up a sink with water.

Keeping the stopper in the drain, stir the water around in one direction, say clockwise. By the way, with the prevalence of digital watches and clocks, do your students these days know what clockwise means? I hope you have an analog clock in your classroom. It might also help to have something floating in the water to make the motion more visible. For instance, sprinkle some pepper on the water right after stirring to see its motion more easily. The students can stir the water with a large spoon, a stick, or, after rolling up sleeves, just with a hand see Figure 2.

Now wait a few minutes until the water is hardly moving and then open the drain. Students will then notice how the water ends up swirling down the drain in the same direction that they stirred it earlier.

Repeat the experiment stirring counterclockwise. Students should conclude that the water swirls down the drain in the same direction that it was initially moving. Do you have extra time to fill? Ha ha.