• # Mysterious and surprising fact!

When the water released in a sink/tub, the water goes down spinning in counter clockwise direction always. Why water is not spinning in clockwise direction and going down?

• It goes such way in north of Equator only. The south of Equator it goes clockwise. I keep forgetting the name of the effect. But this could be due to earths magnetic field. Or just rotation of Earth. Earth is tilted over its axis so it has an abnormal rotation speed in both hemispheres. The speeds are not even. But this effect is held as a misconception by many because the effect can't operate on something so small. This effect is what causes winds around the world and causes currents in oceans. But could it be powerful enough to make a tub of water go its way is a mystery to me.
The stronger a light shines the darker are the shadows around it.

• This is an interesting as well as an intriguing Physics problem often confusing the students. I think students can explore their text books or help books to find out the solution of this.

Meanwhile as I have also read about this, I will like to explain it. The Earth rotation creates a drag on the air in the atmosphere and this effect is known as Coriolis force named after the scientist who discovered it and gave a detailed theory about this peculiar thing. The huge size of the Earth and equally huge atmosphere give rise to this interactive force generated through the relative motion.

That is the reason why during the hurricanes, the air in the atmosphere spins in a counterclockwise direction in the Northern hemisphere and clockwise in the Southern hemisphere.

Now coming to water which is spinning and going down the sink, seeing the small size of the sink and its geometry, the Coriolis force is so feeble and negligible that it can not do any movement in the water body.

So depending upon how you throw the water in it and the slope of the sink floor and other geometrical factors the water going down the sink can rotate in any direction. Coriolis force has nothing to do with it.

So water body in the sink can rotate in any direction.

Knowledge is power.

• After seeing this thread out of my interest I have gone through the internet and read some articles. Some say about Coriolis force. Some say there is no relation between this Coriolis force and water draining down from the sink. Another article I read in which they say the draining of water from the sink will depend more on the shape of the sink and size of the sink. Also, the pipeline design and size and the force of the water flow will also decide the direction of the spinning of the water irrespective of place and other parameters.
From the study, I made what I understood is that we can say that the water body in the sink can rotate in any direction based on the individual position of the sink and other parameters.

drrao
always confident

• Thanks for the responses.
Aditya, I think, you are correct. This is Coriolis Effect. This is due to spinning of Earth over its tilted axis. In northern hemisphere it rotate counter clockwise manner and in southern hemisphere it rotates clockwise manner. Dr Rao,I seriously doubt about your statement that the water body can spin in any direction under gravity. I welcome any contradictory views in this regard.
Hurricanes never crosses equator. Because it has to turn the direction!

• Hurricanes never cross equator won't be a correct statement. Cyclones occur in Indonesia and Australia all the time. Hurricanes and cyclones are the same.
The stronger a light shines the darker are the shadows around it.