Drainage

[may103080]

Hi, I work in a library in NY, and we have been stumped with this question. Why does the water go down the opposite way (counter clockwise?) in Australia then in America. Were assuming it has something to do with the fact that you are on the other side of the world, (or we are on the other side). Can you help us out? Much appreciated! Thank you.Annmarie Jacobs Island Park Public Library

[Island Park Public Library, NY, USAParticipant]

John Thomas is a sweet lil boi

[Island Park Public Library, NY, USAParticipant]

: Hi, I work in a library in NY, and we have been : stumped with this question. Why does the water : go down the opposite way (counter clockwise?) in : Australia then in America. Were assuming it has : something to do with the fact that you are on the : other side of the world, (or we are on the other : side). Can you help us out? Much appreciated! : Thank you.: Annmarie Jacobs : Island Park Public Library

[Island Park Public Library, NY, USAParticipant]

: : : Hi, I work in a library in NY, and we have been : : : stumped with this question. Why does the water : : : go down the opposite way (counter clockwise?) in : : : Australia then in America. Were assuming it has : : : something to do with the fact that you are on the : : : other side of the world, (or we are on the other : : : side). Can you help us out? Much appreciated! : : : Thank you.: : : Annmarie Jacobs : : : Island Park Public Library: : Good Morning : Annmarie to all of your fellow librarians, : The question that you pose about the water going down a drain outlet : the way in which you described can be refered to by having a look at : the information that you may have in the library on the Coriolis Force : and this talks about an abstract mathematical force that appears to act : on objects moving relative to the rotating earth,and is responsible : for the lateral direction of trade winds and for the deflection of projectiles : Now Annmaire all of this sounds high in the head stuff, but if we are to accept : the other laws of nature and the universe then perhaps you should do some : investigation into this concept. : Bye the way on doing an experiement last night by filling up the sink and letting the : water out, in the first instance the water discharged clockwise. We did it again but : this time swirled with my hand the water in the opposite direction but when about two : thirds of the water had run out the water discharging reversed itself back to the : original position, that is clockwise. : Try it out. : Regards : ColinAnnmarie,You have been misled by a well-meaning person. It is a commonly-held belief that water drains differently in the northern and southern hemispheres. Colin is absolutely correct in talking about a thing called the Coriolis force, and it is definitely responsible for large-scale atmospheric phenomena, such as hurricanes, rotating in opposite directions. However, for small-scale things like bathtubs and toilets, the force is WAY too weak to have any observable influence on the direction of drainage. Rather, small tilt or asymmetries in the tub, or the aim of the outlet jets will overwhelm the Coriolis effect, making it unobservable in all but the most exquisitely sensitive and well-designed experiments.Folks like to argue endlessly about this, and in fact, many high schoolers are taught in science class that water drains in opposite directions in the two hemispheres. But thats just plain wrong.You dont have to accept my word for it (just as you should not accept anyone elses without further investigation). Actual calculations can be found at http://www.math.grin.edu/~andrewst/physics/bathtub.htmlGreat question, and I hope you will come to accept the correct answer!–Cheers, Prof. Tom Lee Stanford University

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