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Kinetic energy from rain drops

  1. Oct 17, 2005 #1
    I searched some websites with information about average size and average speed of rain drops, which I used to calculate the kinetic energy of the rain drop just before it hits the ground.
    My original question was: Is ALL this kinetic energy transferred to the ground (assume a non-elastic surface as ground, i.e., glass) or is some absorbed by the rain drop to re-shape itself as it decelerates until its velocity reaches zero?. Thinking twice about it and keeping in mind the typical “crown” shape a drop of water produces when it hits a flat surface, I’m now sure that some of the total kinetic energy carried by the drop just before it hits the floor should be used to split the original drop and “splash” small water drops back up to form the crown shape, decreasing in this way the amount of energy transferred to the ground.
    Now my question has changed: Is this analysis correct? If the answer is YES, how would you estimate how much kinetic energy is lost in re-shaping the water drop and how much is actually transferred to the ground? :confused:
    Any references to websites or papers/research?
  2. jcsd
  3. Oct 17, 2005 #2


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    You need to think about and research surface tension. Sorry, I can't provide any specifics off the top of my head.
  4. Nov 20, 2005 #3


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    Sorry that didn't see this before .... there have been works at least in fields of tribology and wear to study the behavior of rain drops, and all sorts of drops in general. I'd answer your question 'YES' in principle, but giving a quantified answer before "spending a week" doing a fluid-structure coupled analysis is beyond me. Can find some references about work done in this field if you're still interested?
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