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Mass of Earths water (simply)

  1. Jun 5, 2006 #1
    If I've been given the density of water, how do I go about calculating the mass of all the water on Earth.

    Of course, density = m/v, and whilst water covers 2/3 (?) of the Earths surface, how can I work this into the volume? Would it be the 2/3 * surface area of Earth * average depth of the oceans?

    This is assuming that sea water has the same density as fresh water (which is obviously not the case, but still - its what the question states)
  2. jcsd
  3. Jun 5, 2006 #2
    That equation is a good approximation if the surface area of the earth around the depth you are told is comparable to the surface area of the surface of the earth. I'm a little unsure what you're actually given in the question and what you're not, though.
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