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Homework density problem

  1. Aug 30, 2007 #1
    Gold, which has a mass of 19.32 g for each cubic centimeter of volume, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If a sample of gold with a mass of 7.000 oz, is pressed into a leaf of 7.000 μm thickness, what is the area (in m^2) of the leaf? (b) If, instead, the gold is drawn out into a cylindrical fiber of radius 2.400 μm, what is the length (in m) of the fiber?

    I know its simple but I can't seem to know where to get started
     
  2. jcsd
  3. Aug 30, 2007 #2
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    Gold, which has a mass of 19.32 g for each cubic centimeter of volume, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If a sample of gold with a mass of 7.000 oz, is pressed into a leaf of 7.000 μm thickness, what is the area (in m^2) of the leaf? (b) If, instead, the gold is drawn out into a cylindrical fiber of radius 2.400 μm, what is the length (in m) of the fiber?

    I know its simple but I can't seem to know where to get started
     
  4. Aug 30, 2007 #3

    learningphysics

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    Use the equation: density = mass/volume

    For part a) what is the volume of this leaf in terms of thickness and area... use this along with the above equation to solve for area...

    For part b) what is the volume in terms of radius and length... use this with the density equation to solve for height.

    Be careful about units.
     
  5. Aug 30, 2007 #4
    what do you mean by in terms of in terms of thickness and area
     
  6. Aug 30, 2007 #5
    mass is given, density is given. You know the volume then. This volume is fixed. So, get your area (first case) and length (2nd case) accordingly.
     
  7. Aug 30, 2007 #6

    learningphysics

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    Volume = area * thickness
     
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