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Homework Help: Index Notation Help!

  1. Sep 25, 2012 #1
    1. The problem statement, all variables and given/known data

    ∫ ∂k(gixiεjklxl dV

    Can anyone make sense of this? I know I'll need to apply the chain rule when taking the derivative, but I'm not quite sure how to proceed. Also, this is part of a larger problem where g is a gravity vector existing purely in the -z direction, but I treated this as a constant and pulled it outside the integral and got:

    g ∫ ∂k(xiεjklxl) dV

    2. Relevant equations

    3. The attempt at a solution

    I don't think we need to get rid of the integral at all, and I'm pretty sure that the final solution will have something of the form: ∫ x x ( ) dV (that is a cross product). The TA for the course said that we should get to this, and we need to figure out what is inside the parentheses.

  2. jcsd
  3. Sep 25, 2012 #2
    There's no chain rule here; just the product rule. What's [itex]\partial_k x_i[/itex]?
  4. Sep 25, 2012 #3
    If this is tensor notation, then it is simply wrong, because repeated indices there occur all at the bottom. You will have to use LaTeX to make your problem understandable. Speaking of which, knowing what the problem is about would be useful.
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