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Solving Collisions with angles problem

  1. Jun 26, 2011 #1
    First off, i'd like to note that this isn't homework, and i've seen other threads in here that deal with question/equation/problems, so I hope this isn't against the rules. I found this on a practice physics test online. I'm just using it for the benefit of my knowledge, nothing more.

    I can provide the link if necessary for proof.

    Heres the question I want to know how to solve:
    [PLAIN]http://k.min.us/ibDXoi.jpg [Broken]
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Jun 26, 2011 #2


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    Last edited by a moderator: Apr 26, 2017
  4. Jun 26, 2011 #3
    ohhh... I think you put me on the right track for beginning to solve this. The initial momentum was
    in this case. Therefore the conservation of momentum is seen for that X component, I'll have to split them off into the X and Y components of momentum and look specifically at the X/horizontal component of momentum to use the conservation of momentum, if i'm not mistaken?

    4.85 Cos(36o) = 3.92m/s

    p = mv
    p = (0.200kg)(3.92m/s)
    p = 1.2kg•m/s

    Solve for momentum of that object.

    p = mv
    p = (0.200kg)(3.92m/s)
    p = 0.784kg•m/s

    Momentum of the other object (puck 2) is: 1.2kg•m/s - 0.784kg•m/s

    = 0.416kg•m/s [Important: in the x/horizontal direction. need to solve for the angle'd direction]

    0.416kg•m/s ÷ [cos(54o)] =

    0.707741472...kg•m/s !!!!

    I think with "their" answer, they rounded a bit too early.​
    Last edited: Jun 26, 2011
  5. Jun 26, 2011 #4


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    Hi AceInfinity! :smile:
    yes that's fine :smile:

    but there are quicker ways of doing it …

    you could take components in the y direction or in the final direction of puck 2 …

    (both are quicker because they reduce the number of terms)

    try both of those :wink:
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