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#1
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who knows the correct answer?
"maxi" wrote in message news is it true that if you put water in a sink and pull the plug, the water turns the oposite way as in the northern hemisphere? we made a bet and would like to know the correct answer! thx for the help. Max Unless your bath is huge - hundreds of metres wide - and extremely still with no waves or turbulence at all - it will be random. |
#2
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so there is no difference in the turning direction between the northern and
southern hemisphere? "Peter Webb" schreef in bericht ... "maxi" wrote in message news is it true that if you put water in a sink and pull the plug, the water turns the oposite way as in the northern hemisphere? we made a bet and would like to know the correct answer! thx for the help. Max Unless your bath is huge - hundreds of metres wide - and extremely still with no waves or turbulence at all - it will be random. |
#3
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Hi,
so there is no difference in the turning direction between the northern and southern hemisphere? Yes, there is. It does turn the other way round. Ralph |
#4
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"maxi" wrote in message ... so there is no difference in the turning direction between the northern and southern hemisphere? Yes, but as the reply said all other factors would have to be taken out of the equation. In reality this doesn't happen. "Bathwater should drain anticlockwise in the northern hemisphere, clockwise in the southern and straight down at the equator. This is caused by the Coriolis force, a result of the earth's eastward rotation, which in the UK causes water north of the plug to run to the western edge of the hole, while water on the opposite side of the plug moves to the eastern edge, producing an anticlockwise vortex. In Australia, the water should move in the opposite direction. However, the direction of the vortex is easily disturbed by currents in the water, the alignment of the plughole, the shape of the bath, or water temperature, so the phenomenon is difficult to observe." And a little more detail. "If you had a perfectly smooth bathtub in a perfectly round shape, and you filled it full of water, let the water sit for a few days (to let every last bit of turbulence from the filling of the bathtub die out), and then let the water drain though a single hole in the middle of the bathtub, then the water would begin to circulate (counter-clockwise in the northern hemisphere, and clockwise in the southern hemisphere). This is exactly what happens with weather systems. A low-pressure system is just like this ideal bathtub - air is rushing in to the middle of the low pressure system to try and fill the low pressure area, and water is rushing in toward the drain to try and fill it. However, bathtubs and toilets do not have these perfect shapes, and the direction that the water circulates is determines by the shape of the bathtub or by any turbulence that may be present from filling the bathtub. The Coriolis forces are swamped by any minor imperfections. It is possible to estimate the Coriolis forces in a bathtub. If we have a bathtub at the North Pole (where Coriolis forces would be greatest, so assume it is a hot tub so it doesn't freeze), and the bathtub is one meter in radius, and the water drains from the edge of the bathtub to the drain at the center in one second, then the deflection of the water will be less than approximately 0.05 millimeters. This would be measurable, but is rather tiny, and definitely nowhere near the circulation seen in most bathtubs. A larger bathtub or a faster draining rate would amplify the deflection. In short, any "experiment" purporting to show the Coriolis effect in a bathtub, toilet, or pan of water is a fraud, although not necessarily intentional. But a glance at a satellite picture of clouds shows true Coriolis effects without the need for a hottub at the North Pole!" HTH |
#5
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Who Cares!!?
"maxi" wrote in message news is it true that if you put water in a sink and pull the plug, the water turns the oposite way as in the northern hemisphere? we made a bet and would like to know the correct answer! thx for the help. Max |
#6
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Who Cares!!?
You're from QLD, right? ;-) Ralph |
#7
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On Sun, 22 Aug 2004 07:58:27 GMT, in message
, maxi wrote: is it true that if you put water in a sink and pull the plug, the water turns the oposite way as in the northern hemisphere? we made a bet and would like to know the correct answer! thx for the help. The water turns clockwise here in the southern hemisphere[*]. Which way does the water turn in the northern hemisphere? Clockwise or anticlockwise? Is it true that it turns the opposite way as in the southern hemisphere? [*] That's what the coriolis force wants it to do. However, any existing currents in the water [â€*] will almost always have a greater effect. [â€*] Any existing currents great enough to cause the water to travel around in the sink more than once every 24h x cosec(latitude) will have a greater effect. When you fill the sink, it will have small currents greater than this. You'll have to wait a long time for the currents to stop. When you put your hand in the water to grab the plug, you'll create currents greater than this (and mess up the test). -- Cheers, Ralph How To Ask Questions The Smart Way: http://www.catb.org/~esr/faqs/smart-...ns.html#before |
#8
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that is what i call a clear answer!
Thx, I lost my bet "Road_Hog" schreef in bericht ... "maxi" wrote in message ... so there is no difference in the turning direction between the northern and southern hemisphere? Yes, but as the reply said all other factors would have to be taken out of the equation. In reality this doesn't happen. "Bathwater should drain anticlockwise in the northern hemisphere, clockwise in the southern and straight down at the equator. This is caused by the Coriolis force, a result of the earth's eastward rotation, which in the UK causes water north of the plug to run to the western edge of the hole, while water on the opposite side of the plug moves to the eastern edge, producing an anticlockwise vortex. In Australia, the water should move in the opposite direction. However, the direction of the vortex is easily disturbed by currents in the water, the alignment of the plughole, the shape of the bath, or water temperature, so the phenomenon is difficult to observe." And a little more detail. "If you had a perfectly smooth bathtub in a perfectly round shape, and you filled it full of water, let the water sit for a few days (to let every last bit of turbulence from the filling of the bathtub die out), and then let the water drain though a single hole in the middle of the bathtub, then the water would begin to circulate (counter-clockwise in the northern hemisphere, and clockwise in the southern hemisphere). This is exactly what happens with weather systems. A low-pressure system is just like this ideal bathtub - air is rushing in to the middle of the low pressure system to try and fill the low pressure area, and water is rushing in toward the drain to try and fill it. However, bathtubs and toilets do not have these perfect shapes, and the direction that the water circulates is determines by the shape of the bathtub or by any turbulence that may be present from filling the bathtub. The Coriolis forces are swamped by any minor imperfections. It is possible to estimate the Coriolis forces in a bathtub. If we have a bathtub at the North Pole (where Coriolis forces would be greatest, so assume it is a hot tub so it doesn't freeze), and the bathtub is one meter in radius, and the water drains from the edge of the bathtub to the drain at the center in one second, then the deflection of the water will be less than approximately 0.05 millimeters. This would be measurable, but is rather tiny, and definitely nowhere near the circulation seen in most bathtubs. A larger bathtub or a faster draining rate would amplify the deflection. In short, any "experiment" purporting to show the Coriolis effect in a bathtub, toilet, or pan of water is a fraud, although not necessarily intentional. But a glance at a satellite picture of clouds shows true Coriolis effects without the need for a hottub at the North Pole!" HTH |
#9
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Quite simply Yes, and though small the coriolis force is the only force not
acting vertically on the water so the effect is demonstrable visible and consistent. any answers received to the contrary regarding fraud are simply the result of ignorance -- "maxi" wrote in message news | is it true that if you put water in a sink and pull the plug, the water | turns the oposite way as in the northern hemisphere? | | we made a bet and would like to know the correct answer! | | thx for the help. | | Max | | |
#10
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"maxi" wrote in message news is it true that if you put water in a sink and pull the plug, the water turns the oposite way as in the northern hemisphere? we made a bet and would like to know the correct answer! thx for the help. Max Yep thats right www.poms.co.uk |
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