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Homework Help: How much of an iceberg is beneath the surface Archimedes principle

  1. Aug 29, 2010 #1
    How much of an iceberg is beneath the surface....Archimedes principle

    1. The problem statement, all variables and given/known data
    Calculate how much of an iceberg is beneath the surface of the ocean, given that the density of ice is 917kg/m^3 and salt water has density 1025kg/m^3.


    2. Relevant equations

    archimedes principle: buoyancy = to the weight of the displaced fluid

    3. The attempt at a solution
    How can you do this when you're not given area and mass of the iceberg? Can someone guide me with this question?
     
  2. jcsd
  3. Aug 29, 2010 #2
    Re: How much of an iceberg is beneath the surface....Archimedes principle

    Those quantities you don't need will cancel out. It's often hard to see this right away, the best thing to do is to just start solving it manipulating the unknown quantities as variables and just hope for the best.

    In this case, you should write out an equality for what you do know.
    A hint... The volume of the water should be some fraction of the volume of the ice. (x*V) for example would be the volume of the water, where x is the fraction, and V is the volume of the ice.
     
  4. Aug 29, 2010 #3
    Re: How much of an iceberg is beneath the surface....Archimedes principle

    Density ice/density water = volume water/volume ice

    is that rite?
     
  5. Aug 29, 2010 #4
    Re: How much of an iceberg is beneath the surface....Archimedes principle

    Yes that is exactly right.
    The reason I said to look at the volume of water as x*V, because then you can see that (volume of water)/(volume of ice) is equal to the submerged fraction of the ice.
    Volume of water = x*V
    Volume of ice = V
    (volume of water)/(volume of ice) = x
    and x is the fraction of the ices volume that when multiplied gives you the waters volume. Therefore x is equal to the submerged portion of the ice.

    So (Density of ice)/(Density of water)
    is exactly the quantity you were looking for.. Also, if you multiply by 100 then you get the value as a percentage of the total volume that is submerged.
     
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