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Homework Help: The Gunman

  1. Jan 29, 2010 #1
    1. The problem statement, all variables and given/known data
    A gunman shot a bullet with a speed of 10ms-1 which just penetrates into a plank of wood. So with what speed should he fire the bullet so that it passes through 10 similar planks?


    2. Relevant equations
    Newtons equations of motion.


    3. The attempt at a solution
    v2 - u2 = 2as
    v2 is directly proportional to s

    So,
    v21/v22 = s1/s2

    That means
    v22 = 10*10*10
    Therefore
    v = 10 root 10



    Well thats what I have done but I aint sure!!
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jan 29, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi The legend! Welcome to PF! :smile:

    (have a square-root: √ :wink:)
    Yes, that's fine! :smile:

    (btw, you could also have used the work-energy theorem … change in KE = work done = force x distance, is proportional to distance :wink:)
     
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