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Math Help - could somebody help me with this please

  1. #1
    prs
    prs is offline
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    could somebody help me with this please

    A gun of mass 3.5kg fires a bullet of 25g. the gun recoils at a speed of 8m/s-1, Calculate the velocity of the bullet.

    total momentum before explosion=0
    therefore total momentum after exposion=o

    the book shows: m1 v1 + m2 v2,,,,,,, mass1 x velocity1 + mass2 x velocity2 ?
    3.5x(-8)+0.025 v2 =0
    -28+0.025 v2 =0
    0.025 v2=37

    v2=37/0.025 =1480m/s-1

    where does the 37 come from?

    should have done better at school,,,,,,thanks p,
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  2. #2
    MHF Contributor Unknown008's Avatar
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    There must be some mistake in the printing of the book. It is supposed to be:

    0.025v = 28

    v = 1120 m/s
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  3. #3
    prs
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    Thanks 008 i,ll let the college know ,,this is not the first time,,
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  4. #4
    MHF Contributor Unknown008's Avatar
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    No problem

    I myself sometimes to silly calculation mistakes... better not speak about them =S
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