I know there is no truth in people saying water always runs away from sink in clockwise direction, explain plz

Question

I would like a scientific explanation regarding myth of direction water take es to run away down plug hole.

Answer 1

This is indeed a myth. But there IS truth to it :-)
You see, there is this thing, called coriolis force, which is caused by the Earth rotation. It is of the same nature as the cetrifugal force that everybody knows about, but is much weaker, and acts in a different direction.
This force is what's responsible for cyclons in the north hemisphere to spin in clockwise direction, while those in the south hemisphere spin counterclockwise.

If this force was a few tens of times stronger, you would indeed see water in your sink always spin clockwise, unless you are south of equator, where it would be spinning the other way.
But the way things are, this force is just too weak to make any difference, compared to other factors, the influence the direction of the water flow - mostly, it is the construction of your faucet, that makes the water stream fall at a slight angle, which gives it some horisontal speed in that direction, which would take months to dissipate completely.

So, that's how it is - the story about the water flow in the sink itself is a myth, but behind it is a true scientific fact.

Answer 2

It's only true for large scale phenomenon like hurricanes, where those on the northern hemisphere would spin clockwise and those in the southern hemisphere would spin anti-clockwise. This is due to the effects of Coriolis.

Water going through a plughole however is too small to be influenced by this, and thus will go down depending on how you pour the water.

I suspect the myth originates from an extension of the Coriolis effect on hurricanes to water down plugholes.

Answer 3

Coriolis forces arise because the rotational speed at the equator is higher than it is closer to the poles. An air or water mass moving northward or southward from the equator thus has extra momentum relative to the part of the world it is passing over, and is thus deflected.

However, the difference in latitude, and thus angular momentum, between the southern and northern edges of your kitchen sink is so tiny that compared to the general turbulence going on in any container of water, it has no effect. If you could get a bowl of water to be absolutely still, and open the valve at the bottom without causing any turbulence (virtually impossible), you might just see an effect.

Answer 4

There is some truth behind what many say is a myth. Although the coriolis effect is too small to ensure that water always spins clockwise in this hemispere, statistically it flows more often in that direction than the other.

Answer 5

It is a myth to say "water ALWAYS runs...in a clockwise direction." It is a myth because always (and never) rarely occur in physics.

The Coriolis effect is the culprit. It tends to cause fluid in the northern hemisphere to rotate CW and CCW in the southern. But there are so many other things (like the shape of the bowl and placement of the nozzles) that counteract the effect, you cannot categorically say fluid will drain in one and only one direction.

One effect of Coriolis that can be seen regularly is the generally CW direction of winds around a weather low pressure area. Check out:

"The Coriolis effect caused by the rotation of the Earth is responsible for the precession of a Foucault pendulum and for the direction of rotation of cyclones. In general, the effect deflects objects moving along the surface of the Earth to the right in the Northern hemisphere and to the left in the Southern hemisphere. " [See source.]

So as wind tends to flow into the center of a low pressure area, it also tends to move right in the northern hemisphere. This constant movement to the right ends up with the winds circling CW around the center of the low pressure area as they head for that center. Because the winds tend outward from a high pressure area, the Coriolis Effect, still making them turn right, ends up with CCW winds around it.

For Coriolis Effect, check out the source cited below.

Answer 6

You are absolutely correct--this is a total myth. The direction that water rotates is due completely to the design of the drain nozzle. The contribution to this direction based on which hemisphere you are in is negligible--yet people still believe in this myth.

Answer 7

It really is true. It is to do with the gravitational pull of the earth and the way the earth turns. It goes clockwise in the Southern hemisphere and anti clockwise in the Northern.

What we need now is to stand on the equator and see what happens to it there.

Answer 8

It has to do with the gravitational pull. In the southern hemisphere, the water drains counter clockwise.

Answer 9

Clockwise north of the equator, anti - clockwise south of the equator, due to the spin of the earth and the gravitational pull.

You can make it go the other way if you start to swill it the other way as your local swill will be a stronger force.

On the equator it will tend to go on way one day and another way another day because the pull is counter balanced.

Answer 10

Northern hemisphere water swirls clockwise. South of the equator it swirls left. Same is true of rotation of a tornado, hurricane, toilets flushing north of equator.