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Homework Help: Total Kinetic Energy in a System

  1. Apr 10, 2009 #1
    1. The problem statement, all variables and given/known data
    Using the total moment of inertia of the system, find the total kinetic energy of the system.

    Here is the diagram:

    134726A.jpg


    2. Relevant equations
    Find the total kinetic energy of the system using m, r, w.


    3. The attempt at a solution

    For particle a, I found the x and y components of inertia to be mr^2 and 9mr^2 respectively. I found the total y component of inertia of the system to be 11mr^2. I can't seem to find the total kinetic energy. I thought that if you take the original equation:

    K = 1/2mv^2 and plug in the components => K = 1/2m(r^2+9r^2) = 5mr^2 for particle A

    K = 1/2mv^2 and plug in the components => K = 1/2m(r^2+16r^2) = 17/2mr^2 for particle B

    Then add the two quantities to get 27/2mr^2w^2 for the kinetic energy. This isn't right...anything to help me would be much appreciated! Thanks!
     
  2. jcsd
  3. Apr 10, 2009 #2
    ...nvm I am only suppose to use the y-components for some reason. Thanks.
     
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