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Homework Help: Trying to find Velocity and Kinetic Energy!

  1. Oct 25, 2006 #1
    The problem is as follows:

    A 4.0 kg mess kit sliding on a frictionless surface explodes
    into two 2.0 kg parts, one moving at 3.0 m/s, due north, and
    the other at 5.0 m/s, 30 degrees north of east. (a) What is
    the original speed of the mess kit. (b) How much kinetic
    energy was added to the mess kit by the explosion?

    I don't know exactly how to get started with this though I know that there would not be any potential energy so we would have the equation:

    K_1 = K_2
    (1/2)m_1(V^2) = (1/2)m_2(V^2)

    But because the explosion adds kinetic energy to the equation through a non-conservative force we would have the equation:

    K_1 + W_nc = K_2
    (1/2)m_1(V^2) + W_nc = (1/2)m_2(V^2)

    Is this correct in my understanding and if so, where would I go from here to get the original velocity? Thank you very much for your time.

    -Rhaen-
     
  2. jcsd
  3. Oct 25, 2006 #2

    Hootenanny

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    Which quantity is conserved here?
     
    Last edited: Oct 25, 2006
  4. Oct 25, 2006 #3
    It would be the left hand side that is conserved which would make:

    (1/2)m_1(V^2) = (1/2)m_2(V^2) + W_nc

    But what would I do after that if that is the correct equation?

    -Rhaen-
     
  5. Oct 25, 2006 #4

    Hootenanny

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    I was thinking more of momentum.
     
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