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Homework Help: Percent Uncertainty

  1. Aug 16, 2010 #1
    I have 2 problems that I'm wondering if they're right or not... Thanks for the help.

    1. The problem statement, all variables and given/known data
    10) What is the area, and its approximate uncertainty, of a circle of radius 3.8 x 104cm?


    2. Relevant equations
    A=πr2


    3. The attempt at a solution
    A=π380002
    A=4536459792cm2
    Then, I did the same thing with 37999 (the uncertainty is [tex]\pm[/tex] 1) to find the difference in the area to be 238758.
    [tex]238758/4536459792[/tex] x 100% = .0053% uncertainty.

    _______________________________________________________________

    1. The problem statement, all variables and given/known data
    11) What, roughly, is the percent uncertainty in the volume of a spherical beach ball whose radius is r=2.86[tex]\pm[/tex]0.09m?


    2. Relevant equations
    A=[tex]4/3[/tex]πr3


    3. The attempt at a solution
    A=[tex]4/3[/tex]π2.863
    A=97.99m3
    I then did the same thing with 2.77 to get that area to be 89.03m3.
    97.99-89.03=8.96
    [tex]8.96/97.99[/tex]x100%=9% uncertainty.
     
  2. jcsd
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