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Homework Help: Conservation of Momentum Question Involving Two-Dimensions

  1. Sep 22, 2014 #1
    1. The problem statement, all variables and given/known data
    A grenade is rolling due west at 0.954m/s along a floor when it explodes into three pieces of equal mass. The first piece moves at 3.6m/s, 20° [N of W]. The second travels at 5.8m/s, 62° [S of W]. Calculate the velocity of the third piece.

    2. Relevant equations
    a^2 + b^2= c^2
    Tan^-1 to find angle

    3. The attempt at a solution
    My attempt is in the attached image. I was curious if my masses were correct. Since they are all equal, I inputted 1 as my before component, and 1/3 for the 3 after components. Is this correct? And, are my calculations correct as well?

    Attached Files:

  2. jcsd
  3. Sep 22, 2014 #2


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    Regarding the masses: You could simply assume that the grenade has a total mass ##m##, which will make the parts have mass ##m/3##. You will notice that ##m## cancels out of the final answer and thus that it does not matter what you chose for ##m##. In particular, ##m = 1\,\rm kg## should give the correct answer just as well as any other mass.
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