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Coriolis movie of draining pool?

  1. Jun 29, 2013 #1
    So we all know the Coriolis effect isn't demonstrated in a bathtub or toilet. Are there any videos online of the size of pool needed to demonstrate it? I saw one in grad school--black and white from the '50s--an indoor, above-ground pool with a drain in the center, allowed to settle for a week before the drain was removed. Haven't found anything like it make it to the Web, despite searching off and on for a year. Anybody else find something similar? Would help my class discussion a little...

  2. jcsd
  3. Jun 29, 2013 #2


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    "In 1908, the Austrian physicist Ottokar Tumlirz described careful and effective experiments which demonstrated the effect of the rotation of the Earth on the outflow of water through a central aperture. The subject was later popularized in a famous article in the journal Nature, which described an experiment in which all other forces to the system were removed by filling a 6 ft (1.8 m) tank with 300 US gal (1,100 L) of water and allowing it to settle for 24 hours (to allow any movement due to filling the tank to die away), in a room where the temperature had stabilized. The drain plug was then very slowly removed, and tiny pieces of floating wood were used to observe rotation. During the first 12 to 15 minutes, no rotation was observed. Then, a vortex appeared and consistently began to rotate in a counter-clockwise direction (the experiment was performed in Boston, Massachusetts, in the Northern Hemisphere). This was repeated and the results averaged to make sure the effect was real. The report noted that the vortex rotated, "about 30,000 times faster than the effective rotation of the earth in 42° North (the experiment's location)". This shows that the small initial rotation due to the earth is amplified by gravitational draining and conservation of angular momentum to become a rapid vortex and may be observed under carefully controlled laboratory conditions."
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