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Homework Help: Determining Whether An Object Is Actually Gold

  1. Sep 12, 2007 #1
    A gold crown hangs from a spring scale reading it's mass as 14.7 Kg. When the crown is submerged in water while still hanging from the spring scale, it's mass now reads 13.4 kg. Knowing that its either all gold, or a gold and copper compound, figure out which of the two it is. If it is a gold and copper compound, what are their ratios. Density of Au=19.32, Density of Cu=8.96.

    I'm stuck, not really even sure where to start. :(. Any tips or help would be greatly appreciated. I do not by any means want anyone to do this for me. A nudge in the right direction would be great.
  2. jcsd
  3. Sep 12, 2007 #2


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    A law of buoyancy says the difference between the two weights is the weight of fluid displaced. Is that enough of a nudge?
  4. Sep 12, 2007 #3
    More simply put: The buoyant force is equal to the weight of the displaced fluid.
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