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Homework Help: Find the buoyant force on the iceberg

  1. Jun 10, 2010 #1
    1. The problem statement, all variables and given/known data

    A 6500-kg iceberg with density 931kg/m^3 is afloat in seawater with density 1030kg/m^3. a) Find the buoyant force on the iceberg b) the volume of water displaced by the iceberg c) The fraction of the icebergs volume that is below the waterline.

    2. Relevant equations

    Fb = pgV

    V = (mg -Wa)/pg

    3. The attempt at a solution

    I have tried everything this is one of the hardest questions for this part. All solutions i have attempted end up equalling themselves or 1 or 0 or something u knw. Im guessing some sort of simultaneous equation setup is need or find the fraction of the Volume that is underwater first somehow but i just cant get there. If someone who has done this sort of prob bfore can tell me the secret ill b happy :D. CHeers.
  2. jcsd
  3. Jun 10, 2010 #2
    i'll have a go

    a) It says its afloat right? So therefore the buoyant force must be pushing up the entire weight of the iceberg. How much does the iceberg weigh?

    b)volume of water displaced by the iceberg will equal the fraction of the iceberg's volume that is under the ocean. only some of the iceberg is under the sea and some is above. this fraction is determined by the densities: 931/1030. so now we know the fraction, we just multiply it by the volume of the iceberg (determined by density and mass of berg).

    c) fraction below the water is as mentioned 931/1030 and hence fraction above the water will be 1 minus the above fraction.

    sounds about right to me but i'm not willing to bet a testicle
  4. Jun 10, 2010 #3
    nice one thanks for the reply. I didn't think anyone was game enough to give it a go lol. You are actually right for a) i didn't think that it would be the equivalent of the whole weight but it was! after that everything else falls into place. thanks heaps for ur help mate :D
  5. Jun 10, 2010 #4
    no problemo i'm learning too so its fun when i can actually do problems lol
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