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Differentials Problem

  1. Jan 27, 2007 #1
    1. The problem statement, all variables and given/known data
    Sorry, this may sound dumb, but How do I use differentials to estimate the amount of tin in a closed tin can with diameter 8 cm and height 12 cm if the tin is 0.04 cm thick?

    2. Relevant equations
    The volume of the can is V = pi*r^2h. So dV= 2*pi*rh*dr

    3. The attempt at a solution

    Could someone point out what I am doing wrong? I thought that since volume is pi*r^2h, and so dv = 2*pi*rhdr. So, wouldn't I just plug in 2*pi*4*12*0.04 to arrive at an estimate of the amount of the tin? Thanks so much!!
  2. jcsd
  3. Jan 27, 2007 #2
    You are correct =).

    V = pi * r^2 * h
    dV = 2 * pi * h * r * dR
    dV = 2 * pi * 12 * 4 * 0.04
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