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Homework Help: Collisions problem

  1. Feb 13, 2008 #1
    1. The problem statement, all variables and given/known data

    a 600 kg canon, initially at rest, exploded upon firing and broke in to three fragments. One fragment of mass of 200 kg travelled east at 40m/s and a second fragment of mass 300 kg travelled due south at 20 m/s. What was the velocity of the third fragment?

    2. Relevant equations

    sum of P = sum of P'
    0= P1 + P2 + P3

    3. The attempt at a solution

    I'm not sure whether I'm supposed to use trig or something to find the missing velocity.
    Any help would be GREATLY appreciated.
  2. jcsd
  3. Feb 13, 2008 #2


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    Momentum is a vector quantity, and as such, the sum of the momenta must obey the laws of vector additions. Are you familiar with resultants and vector sums?
  4. Feb 13, 2008 #3
    This is what I have so far. Am I on the right track?
    Will the resultant be the hypotenuse?


    Attached Files:

  5. Feb 13, 2008 #4
    I did Pythragoras to find the missing vector.

    (8000)^2 + (6000)^2 = c^2
    c=100 m/s

    tan[tex]\theta[/tex] = 6000/8000
    [tex]\theta[/tex] = 37

    I got 100 m/s for my velocity and 37 degrees N of W. Is this right?
  6. Feb 14, 2008 #5
    You know anythin about momentum conservation????
  7. Feb 14, 2008 #6


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    Yes, that is correct, but your diagram and equation are not consistent with this answer. Looks like you combined a step when solving for 'c' , and the direction of the diagonal is wrong.
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