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I Center of Mass Velocity in Multiple Dimmensions

  1. Aug 13, 2017 #1
    I was doing some practice problems to become more familiar with the Center of Mass Velocity and I came across this one from (Noted in the picture) Engineering at Illinois, that relates the velocity of the center of mass in both the x and y direction, however I don't quit understand the answer.

    VCM = (M1V1 + M2V2)/ Mtotal

    Since this is the case VCM should equal 2.4, but the question asked for the velocity in the x and y direction

    Since only one object is moving in the x-direction shouldn't that be the VCM for the x-direction??
    Why would VCM (x-direction) = Momentum in the x-direction? How would one go about calculating VCM for individual dimensions? Thanks!
  2. jcsd
  3. Aug 13, 2017 #2


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    No. As you see in the formula,
    There are factors ##m_1/m_{\rm total}## and ##m_2/m_{\rm total}##

    It isn't. ##v_{\rm} \;m_{\rm total} ## is the momentum.
  4. Aug 13, 2017 #3


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    The easiest way to do it is to remember that velocity is a vector, which you seem to have forgotten when you got your 2.4m/s answer.
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