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Homework Help: I neeed help desperatly

  1. Sep 13, 2005 #1
    hi again
    i need help with this question!!!
    One cubic meter (1.00 m3) of aluminum has a mass of 2.70×103 kg, and 1.00 m3 of gold has a mass of 1.93×104 kg. Find the radius of a aluminum sphere whose mass is the same as that of a gold sphere of radius 1.70 cm.

    i tried it over 15 times every time i enter an answer, it says "Please adjust significant figures, you provided 2 significant figures"
    my answer was 0.017m
    what do u think...plzzzzz help me
  2. jcsd
  3. Sep 13, 2005 #2
    0.017m is 2 sf. Try 3 sf, 0.0170m.
  4. Sep 13, 2005 #3


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    Gold Member

    All of the information was given with 3 significant figures and its all multipliction and division to get the answer, so you should give the answer to 3 sig figs. That would make your answer .0170m instead of .017m, but I don't believe that is the correct answer. Remember that the mass is the density times the volume. So the volume of the gold sphere times the density of gold equals the volume of the aluminum sphere times the density of aluminum. Put the equations in for the volume of the spheres in terms of their radii, and solve for the unknown radius of the aluminim sphere.
  5. Sep 13, 2005 #4
    it is still the wrong answer im gonna try leonhardeuler's way thanks anyways
    it is so complicated i donno how to make it simpler
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