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B Finding Constant value K

  1. Mar 16, 2017 #1
    I'm working on a problem about a spherical balloon as its inflated slowly the radius of the balloon is in cm and the time is in seconds

    dr/dt = k/r2

    Now I know how to rearrange this equation using separable differentiation


    However I would like to find the value of the constant K

    For example the radius is 6cm and the radius is increasing at the rate of 5/36pi cm per second and I would like to rearrange the dr/dt=k/r2 to find the value of K

    Any help would be appreciated
  2. jcsd
  3. Mar 16, 2017 #2


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    Science Advisor

    You are given dr/dt (5/36pi cm per second) at a given r (6cm). Plug these into your first equation and solve for k.
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