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Index of Subjects Would it turn counter clockwise in the Southern Hemisphere? Why or why not? Cheers, Joan David & Alison Webster wrote: > Dear All, Jan 22, 2007 > I put a saucepan of water onto a piping hot wood stove tonight and > a few minutes later wondered why someone had left the bathroom fan on. > The 'fan' turned out to be sound produced by up and down oscillation > of the saucepan about 10 times a second and with an amplitude, at the > end of the handle, of about 3 mm. > > The pan has a slightly rounded bottom from having run out of water > several times and, presumably because the rounding is a bit lop-sided, > the pan when oscillating also graduallly turns clockwise as viewed > from above. To start this oscillation, one must set the pan onto the > stove with the handle up ~one cm from level and with no sideways slop > of water. Once the oscillation is started then it continues until the > pot handle rotates around enough to touch the back of the stove or > until the water starts to ping. > > Some 12 years ago I saw oscillation of this type involving a larger > pot, which of course also had a rounded bottom, a 7' long steam box > that was balanced on the pot, a period that (I think) gradually > increased to about 4 sec and amplitude that gradually increased to > about one foot [at which point I steadied the box & put a prop under > one end]. > Having something barely balanced (handle & pot or box much longer > than pot diameter along with rounded pot bottoms) is probably a > necessary condition as is a relatively hot surface but I have yet to > fathom how heat drives the oscillation. Any ideas ? > > It does not appear to be related to surface tension effects > because adding a drop of detergent to an oscillating pot had no > effect. It can be difficult to duplicate and may be dependent upon > some subtle configuration of the rounding that changes with recent > heating and/or something related to rate of heat transfer (e.g. a cold > pot and a brisk fire). After starting it 10-15 times without a hitch, > after I first noticed it, I can not now get a sustained oscillation. > > Yours truly, Dave Webster, Kentville > > >
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