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Homework Help: Average friction force(energy)

  1. Mar 31, 2010 #1
    1. The problem statement, all variables and given/known data

    A 16 g bullet pierces a sand bag 13cm thick. If the initial bullet velocity was 51m/s and it emerged from the sandbag with 14m/s, what is the average magnitude of the friction force the bullet experienced while it traveled through the bag?

    2. Relevant equations

    k+u=k+u?

    3. The attempt at a solution
    I am completely stumped on this equation, i think my problem is that i keep thinking kinematics but i dont believe that is how we are supposed to solve it as we are currently working on energy
     
  2. jcsd
  3. Mar 31, 2010 #2

    rl.bhat

    User Avatar
    Homework Helper

    Work done due to frictional force = change in KE.
     
  4. Mar 31, 2010 #3
    lol thanks
     
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