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Homework Help: Radius of gyration

  1. Oct 23, 2011 #1
    With <Rg^2>=1/N [sum[(Ri-Rc)^{2}>] where Rc is the center of mass, =1/N sum Ri, and provided that <R^2>=2Lζ .Show that sqrt(R^{2})=sqrt(L ζ /3)
    Last edited: Oct 23, 2011
  2. jcsd
  3. Oct 23, 2011 #2


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    It would perhaps help if you defined all the variables, and what the problem is actually asking...
  4. Oct 23, 2011 #3
    <Rg^2> is the radius of gyration. Ri-Rc is the distance between the monomers and the center of the polymer. The problem is that give <Rg^2>=1/N Sum<( Ri-Rc )^2>, and that Rc=1/N sum Ri. proof that sqrt(<Rg^2>) = sqrt(Lζ/3). Actually i was working on it, and there is a step that i m not sure, and it's that if 1/N Sum<(Ri-1/N Sum(Ri)>^2 ==1/(2N^2) <sum of [i,j] (Ri-Rj)>^2
    Last edited: Oct 23, 2011
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