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The capillary action's limit

  1. Mar 22, 2014 #1
    Is it feasable to achieve elavation of water to, let's say, 10 m height due to the capillary action effect ? Or the capillary diameter for that to achieve should be less than the water molecules themselves ?
     
  2. jcsd
  3. Mar 22, 2014 #2

    Integral

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    I do not believe that it is pure capillary action, but water does reach the top of 100m tall trees.
     
  4. Mar 22, 2014 #3
    That happens due to negative pressure at the top of the tree (otherwise known as tension). You might think a liquid cannot have negative pressure but that would be wrong. Water is actually in a metastable supercooled state at the top of the tree and would boil (due to negative pressure) if a nucleation seed was provided.

    Watch Veritassium's youtube video titled "The Most Amazing Thing About Trees" for a clear explanation.
     
  5. Mar 22, 2014 #4

    A.T.

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    The pores of the leaves (where the water evaporates) are indeed so tiny (2-5 nm), that capillary action is strong enough to balance the weight of the sap column below, within which the force is transmitted as tension (negative pressure) in the much thicker xylem-tubes (20000-200000 nm).

    https://www.youtube.com/watch?v=BickMFHAZR0
     
  6. Mar 23, 2014 #5
    I meant artificial material.
     
  7. Mar 23, 2014 #6

    UltrafastPED

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  8. Mar 23, 2014 #7
    :
    ".........venerable question of why sap rises in tall trees [32]. We
    hope to address this problem in future work"
     
  9. Mar 23, 2014 #8

    A.T.

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    See post #4. The xylem tubes in the tree stem are too wide to pull the water 100m by capillary action. But the much smaller pores in the leaves provide enough capillary action to balance the weight of the fluid column below, which is under tension.
     
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