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Degrees of freedom

  1. Oct 23, 2013 #1
    How is for rigid body made up of n particle, the degree of freedom is 3n-nC2.i can understand that degree freedom of n particle is 3n and suppose you have 2 particle whose distance between them is fixed, then degree of freedom is n 3(2)-1=5.if we have three particles then it is 7.
    Therefore n particle whose distance between them is fixed have degree of freedom which is 3n-(n-1) .how can it be 3n-.nC2.
  2. jcsd
  3. Oct 23, 2013 #2


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    What is C2?
  4. Oct 23, 2013 #3
    It does not matter how many particles a rigid body is made of (except when all of them are collinear). It always has 6 degrees of freedom. 3 rotational (Euler angles), and 3 translational. All-collinear rigid bodies, even though the term "body" is hardly applicable here, lose one rotational DoF.
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