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Homework Help: Momentum/exploding block

  1. Feb 1, 2007 #1
    1. The problem statement, all variables and given/known data

    A 2 kg block moves north at an unknown velocity. It then explodes into two blocks, the first one being 1.2 kg and moves EAST at 10 m/s, the second one is 0.8 kg and moves 22 m/s at an angle North of West.

    What is the initial MOMENTUM of the 2kg block?

    2. Relevant equations

    p initial = p final (momentum conserved)

    3. The attempt at a solution

    The answer i got was 13 kg m/s, and some friends of mine got 29.6 kg m/s. The reason i got 13 is because I think/thought the two horizontal components of the exploded blocks cancel out each other because they are in seperate directions (velocity is a vector and therefore one being negative one being positive, so I thought only the vertical component of the second block's momentum mattered).

    Any help is appreciated Thank You!
     
  2. jcsd
  3. Feb 1, 2007 #2

    Doc Al

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    Staff: Mentor

    You are correct; your friend is not. Good reasoning.
     
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