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Homework Help: Rolling water

  1. Oct 7, 2007 #1
    1. The problem statement, all variables and given/known data
    So I need to get a rough calculation:
    At what angle does drops of water start rolling down a plane of glalss.
    This is for my project where we are using a solar still to purify water. I just need ot get a rough calculation so I know at what angle to tilt the plane of glass. I am aware that I could experiment but for the class I need calculations.
  2. jcsd
  3. Oct 7, 2007 #2


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    Science Advisor
    Homework Helper

    Surface tension is what is stopping the drops from moving.
    You will need to investigate what parameters effect the surface tension - this is going to be dominated by the nature of the glass surfacd, how smooth, what type of glass (surface charge) and any impurities on the surface ( particulalry detergents).

    There isn't a single number for just glass.
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