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Homework Help: Calculating the mass of objects in ICE

  1. Aug 16, 2008 #1
    1. The problem statement, all variables and given/known data

    A rectangular block of ice containing a fossil measures 426mm x 264mm x 153mm with a total mass of 21.8kg

    Density of ice = 0.917g/cm3

    Density of Fossil = 3.64g/cm3

    What percentage of the block's mass is the fossil?

    2. Relevant equations

    Density = Mass/Volume
    Mass = Density x Volume
    Volume = Mass/Density

    3. The attempt at a solution

    Now I calculated the volume 17206992 but I thought that was too big so I changed the measurements to cm = 42.6cm x 26.4 x 15.3 V= 17207cm3

    Now this is were it gets a bit hairy I calculate the Mass

    M = Density x Volume = 0.917g/cm3 x 17207cm3 = 15778.81g = 15.77kg (ICE)

    M = Density x Volume = 3.64g/cm3 x 17207cm3 = 62633.48g = 62.63kg (FOSSIL)

    What have I done wrong here? I am not sure of the correct steps?
  2. jcsd
  3. Aug 16, 2008 #2


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    Science Advisor
    Homework Helper

    You know volume(fossil)+volume(ice)=total volume. Also density(fossil)*volume(fossil)+density(ice)*volume(ice)=total mass. That's two simultaneous equations in two unknowns. Solve for the two unknown volumes.
  4. Aug 16, 2008 #3
    What about if take the 21.8kg convert it to grams 21800g minus the total mass of ice 15778g

    Will that mean 21800-15778 = 6022g is the mass of the Fossil ? Surely it can't be that simple? Have I missed a step ?
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