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Angular Momentum Dimensional Analysis

  1. Mar 11, 2014 #1
    1. The problem statement, all variables and given/known data
    "A particle of mass m moves in a circle of radius R. Using dimensional argument,
    determine the particle angular momentum."

    2. Relevant equations
    L = mvr


    3. The attempt at a solution
    Because L = mvr, the dimensionality would be ML2T-1. I don't know where to go from here so if someone could point me in the right direction it'd be appreciated.

    Thanks!
     
  2. jcsd
  3. Mar 11, 2014 #2

    DrClaude

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    Staff: Mentor

    You need to take the problem backward, compared to what you wrote.

    To use a "dimensional argument," you start by the units, and then figure out how to construct an equation (with parameters you know) that will have the correct units.

    So start with the fact that the units of angular momentum are ML2T-1, and find a way to argue that this means that ##L = m v R##.
     
  4. Mar 11, 2014 #3

    DrClaude

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    Staff: Mentor

    I should add that dimensional arguments are, at best, correct up to a dimensionless constant.
     
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