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Homework Help: Find the final momentum

  1. Nov 5, 2008 #1
    1. The problem statement, all variables and given/known data

    A red ball is heading due east, a blue ball is moving due west, and a green ball is moving north. They have initial speeds vr,i=20 cm/s, vb,i=10 cm/s, vg,i=10 cm/s. The red ball has a mass of 5 g, the blue ball has a mass of 10g, and the green ball has a mass of 5g. The three balls all collide, and stick together. Find the magnitude and direction of the final momentum of the composite.

    2. Relevant equations
    the sum of PI=the sum of PF

    3. The attempt at a solution
    Ok...without plugging the numbers in this is what I have so far:
    I don't really know how to approach this problem, so if someone could tell me if I am starting it on the right path would be great.
    I broke it up into x and y components, and for the x component of momentum I have:

    Then for the y component I have:

    Am I on the right track...or completely missing the point?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Nov 6, 2008 #2


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    Science Advisor
    Homework Helper

    Hi ScullyX51! :smile:
    Yes, that is exactly the right track … :smile:

    momentum is a vector, and so it obeys the laws of vector addition …

    sometimes physics is that easy! :wink:
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