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Homework Help: Surface Tension and Insects

  1. Aug 26, 2009 #1
    A rare species of insect about 1.5mm in diameter floats fully submerged just beneath
    the surface of the water in lakes and ponds. When threatened, it responds to danger
    by exuding a noxious substance from its tail that changes the surface tension on the
    skin of its tail. As a result the insect accelerates, shooting quickly across the water.
    Explain in detail why this occurs, and estimate the maximum velocity such an insect
    would be likely to achieve, and which direction the bug accelerates. The surface
    tension of water is 0.072 N m–1 and the viscosity is 10–3 Pa s.

    Don't solve it or anything yet. I'll post my attempt at an answer at a later time. Just needed to post the question now.
  2. jcsd
  3. Aug 27, 2009 #2
    Okay, so I looked up a couple of books and found that this phenomenon is explained by the Marangoni propulsion. I don't really know what it means. Can someone please explain the Marangoni Effect for me please?
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