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Homework Help: Determine the initial speed of the bullet

  1. Jun 29, 2010 #1
    1. The problem statement, all variables and given/known data
    An 8.00 g bullet is fired into a 160 g block that is initially at rest at the edge of a table of 1.00 m height. The bullet remains in the block, and after the impact the block lands d = 2.2 m from the bottom of the table. Determine the initial speed of the bullet.


    2. Relevant equations
    y=voyt + 1/2 gt2
    vox = x/t
    mbvb = (mb + mB) v


    3. The attempt at a solution
    y=voyt + 1/2 gt2
    t2=-2(1m)/9.8 m/s2
    t=0.45s

    vox = x/t
    vox = 2.2m / 0.45s
    vox= 4.889 m/s

    mbvb = (mb + mB) v
    vb= ((0.008 kg + 0.160kg)/0.160kg) 4.889 m/s
    vb=5.13 m/s
     
  2. jcsd
  3. Jun 29, 2010 #2

    kuruman

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    Re: momentum

    Is there a question you wish to ask?
     
  4. Jun 29, 2010 #3

    collinsmark

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    Re: momentum

    Hello mandy9008,
    Your approach is good so far, :approve:, but be careful of your precision (significant digits). I think you should carry out your '0.45 s' term to a couple more digits here.
    You're dividing by the mass of the block. Is that what you really want to do? :wink:
     
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