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Homework Help: Buoyancy of Spheres: max mass added without sinking

  1. Dec 10, 2008 #1
    1. The problem statement, all variables and given/known data

    Styrofoam has a density of 300 kg/m3. What is the maximum mass that can hang without sinking from a 40-cm-diameter Styrofoam sphere in water? Assume the volume of the mass is negligible compared to that of the sphere.

    2. Relevant equations

    FB=poVog
    Volume of sphere: 4/3 π r3
    p=m/V

    3. The attempt at a solution

    I tried this:
    mo/3.35 m3=300 kg/m3
    Therefore,
    mo=1005 kg

    So,
    To find the exact amount of mass added to the Styrofoam sphere to sink in water:
    1005k + m2/3.35 m3=1000 kg/m3

    Therefore:
    m2=2345 kg

    This is obviously an obscenely large mass to make Styrofoam sink in water. Any help is appreciated.

    Best,
    Quixote
     
  2. jcsd
  3. Dec 10, 2008 #2

    rl.bhat

    User Avatar
    Homework Helper

    Check the volume of the sphere.
     
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