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2D Momentum and Collisions Lab Help Grade 12

  1. Apr 12, 2012 #1
    1. The problem statement, all variables and given/known data

    For a lab, I have performed a completely inelastic collision using 2 masses. One mass is 0.583 kg, and the other is the unknown we have to find. Using an air table, I was given the dots to show the movements of the objects as they intersect and them move together. I have broken them into components and solved for the velocity and the momentum for each. Well, thats where the problem is:

    Momentum of the known mass:

    m1v1 = p1
    m1x(v1x) = p1x
    m1y(v1y) = p1y

    Same thing for the second mass, except it is m2, an unknown.

    When they move together, I know the mass will be the total (m1 + m2, which i state as m3) and the velocity will also be something else, v3.

    Now, the problem:

    I am trying to do m1v1 + m2v2 = m3v3 to find the unknown mass Question is, how would i rearrange the equation to find this m2.


    2. Relevant equations

    mv = p
    1/2mv^2

    3. The attempt at a solution

    I am just trying with the 'x' component for the example:

    m1 = 0.583 kg
    v1x = 0.18 m/s [E]

    m2 = unknown
    v2x = 0.29 m/s [W]

    m3 = m1 + m2
    v3x = 0.05 m/s [W]

    m1v1 + m2v2 = m3v3

    How can i find this mass, it cancels out the moment I bring one of the m2's to the other side , I am I making some mistake here? I know it may not seem like I did any work, but I have pages of work getting to this part haha.
     
  2. jcsd
  3. Apr 12, 2012 #2
    what else could you call m3?
     
  4. Apr 12, 2012 #3
    m3 is (m1 + m2)
     
  5. Apr 12, 2012 #4
    i think you should show your work so far. there is no reason anything should cancel out.
     
  6. Apr 13, 2012 #5
    I got it, thanks.
     
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