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Homework Help: Forming Linear Equations From Non-Linear Equations

  1. Nov 10, 2005 #1
    For my first year formal lab im having a little bit of trouble with one aspect, lets see if anyone can help

    Im trying to rearrange the equation

    T = 2pi [(32 L I)/(pi S d^4)]^1/2

    ....(sorry, i dont know how to use the better way of displaying math) to form a linear equation so it can be graphed as a line, but im having a rough time of it. My biggest problem seems to be getting the + b segment (for the form y=mx+b), the + sign doesnt seem to want to show up when the origional equation is all multiplication. Any help would be appreciated.
  2. jcsd
  3. Nov 10, 2005 #2


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    Homework Helper

    Which are variables and which are constants.

    The simplest way of linearising products of things to various powers is simply to take logs.
  4. Nov 10, 2005 #3
    Its an equation relating to a torsional pendulum with a metal disk at the end

    I = moment of inertia for disk
    L = length of suspending wire
    S = shear modulus
    d = diameter of suspending wire
    T = period of rotation

    the constants are S d and I

    i think i need to graph T against L somehow
    Ill give the log thing a shot
    Last edited: Nov 10, 2005
  5. Nov 10, 2005 #4
    how does this sound, checking to see if im in the ball park

    T^2 = {[4 pi (32) I]/(S d^4)} L

    where T^2 = y L = x and everything in {} is m, guessing b doesnt apply here and any intercept on the graph can be attributed to error
    Last edited: Nov 10, 2005
  6. Nov 10, 2005 #5
    That would work provided you don't change the parameters in the { }.
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