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Surface area of N spherical droplets?

  1. Sep 9, 2007 #1
    1. The problem statement, all variables and given/known data

    I have the following problem
    Assume that 30.0 cm^3 of gasoline is atomized into N spherical droplets, each with a radius of 2.00 x 10^-3 m. What is the total surface area of these N spherical droplets?

    2. Relevant equations
    SA = 4 * pi *r^2
    V = 4/3 * pi * r^3


    3. The attempt at a solution
    SA of each atom is 5.03x10^-9
    V = 3.35x10^-14
     
    Last edited: Sep 9, 2007
  2. jcsd
  3. Sep 9, 2007 #2

    G01

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    Ok, think about this.

    What is the total surface area of all the spheres in terms of N?

    What is the total volume of all the spheres in terms of N?

    If you can answer these questions you should be able to eliminate N, allowing you to solve for The surface area.
     
  4. Sep 9, 2007 #3

    Kurdt

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    Have you worked out how many droplets there are?
     
  5. Sep 9, 2007 #4

    Dick

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    Ignoring the fact both SA and V of the droplets are both very wrong and lack units (you can do better than that!). Total volume before equals total volume after. Use that to solve for N.
     
  6. Sep 9, 2007 #5
    The values are wrong...?
    I know the units of area of is m sqrd and volume is m cubed, but as far the values go, has my calculator betrayed me?
     
    Last edited: Sep 9, 2007
  7. Sep 9, 2007 #6

    Kurdt

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    You are given a volume of gasoline and told it is turned into N small spheres. You are given the radius of the spheres and thus you can work out the volume and surface area. You know what the volume is and so you can find out how many droplets there are. Then you can find the total surface area.
     
  8. Sep 9, 2007 #7
    Muahahahahaa! I got it :)
    I am going to go ahead and say I love you guys. Thank you for all your help.
    Next time you guys are in germany, bring lots of lube.
     
    Last edited: Sep 9, 2007
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