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Find the magnitude and direction of the sum of momenta

  1. Jul 6, 2007 #1
    1. The problem statement, all variables and given/known data


    An 85 kg jogger is heading due east at a speed of 2.2 m/s. A 55 kg jogger is heading 20° north of east at a speed of 4.0 m/s. Find the magnitude and direction of the sum of momenta of the two joggers.

    2. Relevant equations

    The Impulse-Momentum Theorem

    3. The attempt at a solution

    I tried to get the components of the 2 vectors, add them, and get the answer...but I got the wrong answer apparently. Should I try again?
     
  2. jcsd
  3. Jul 6, 2007 #2

    Doc Al

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    Staff: Mentor

    Yes, try it again--that's the right method. Remember that you are adding momenta, not just velocity vectors.

    This has nothing to do with the impulse-momentum theorem.

    Also: Try to give your posts more descriptive titles that "Help!". :wink:
     
  4. Jul 6, 2007 #3
    haha well obviously "help" gets a much desired response =) but i'll keep that in mind. and webassign is wrong a lot. it said to use the theorem. how would i use momenta instead?
     
  5. Jul 6, 2007 #4
    Ok, I got it. Thanks!
     
  6. Jul 6, 2007 #5

    Doc Al

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    Staff: Mentor

    Don't worry about the getting help part--that's what the "homework help" forums are for. But if all your posts have the same title, busy homework helpers might think they've already answered your question--thus you end up getting less help than you might need.
    That's what I thought you already tried. Find the components and add them up. This is an addition of vectors problem, not an impulse-momentum problem. (Unless there is more.)
     
  7. Jul 6, 2007 #6

    Doc Al

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    Staff: Mentor

    Good! .... :smile:
     
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