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Homework Help: How do I calculate the impulse

  1. Oct 3, 2006 #1
    If I'm given an object with X mass that is moving in one direction at Y velocity, then changes direction and moves at Z velocity, how do I calculate the impulse? Most equations I have are concerned with time intervals; this one is not.
     
  2. jcsd
  3. Oct 3, 2006 #2

    radou

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    Homework Helper

    The impulse equals the change of linear momentum.
     
  4. Oct 3, 2006 #3
    Impulse
    = Change of momentum
    = Final momentum - initial momentum
    = mv - mu
    = m(v-u)
    = X (-Z-Y)

    Assuming what you are talking about is linear momentum. I would be a lot more complicated and you would have to calculate is as an oblique collision if it were not.
     
  5. Oct 4, 2006 #4
    say the object moves at 3.6 m/s initially, then gets hit and moves -24.2 m/s in the other direction; m=.41kg

    3.6(.41)=1.476
    -24.2(.41)=-9.922

    =-8.446 <--is this right?
     
  6. Oct 4, 2006 #5

    Doc Al

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    Staff: Mentor

    No, impulse equals change in momentum, which is final minus initial.
     
  7. Oct 5, 2006 #6
    It is best you don't try to calculate the values of the momentum separately. Just calculate it using the formula I gave. The result you would get will be the sum of the magnitudes, not what you got.
     
  8. Oct 5, 2006 #7

    Doc Al

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    Staff: Mentor

    The only mistake mikefitz made was not subtracting correctly.
     
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