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Homework Help: Question with Archimedes' principles

  1. Oct 12, 2011 #1
    A cylindrical fishing float is 15cm long, with an average cross section of 3cm^2. It is made of polystyrene and has negligible mass. A lead weight of 30g is attached to the bottom of the float using a thin nylon monofilament line.

    Question: Calculate how far the float will sink into the water.

    Treat g as equal to 10N kg-1

    I know Archimedes said upthrust acting on a body is equal to weight of fluid displaced but can't see how to apply that in this case. Thanks for any help.
  2. jcsd
  3. Oct 12, 2011 #2
    Can you find an expression for the volume of the water displaced based on the shape of the float? In this case the density of water can be used to find the mass of the water displaced.
  4. Oct 12, 2011 #3
    Thanks for your help. I've come up with an answer of 0.1m?
  5. Oct 12, 2011 #4
    You're welcome, I get the same answer.
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