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Homework Help: Bullet shot through stationary wooden block

  1. Jul 17, 2012 #1
    1. The problem statement, all variables and given/known data

    So I have a block that has had a bullet shot through it at an initial speed of 280m/s. It is 0.03kg and after it leaves the block it is travelling at 190m/s. The block is a length of 0.012m and weighs 1.50kg. What is the average force exerted on the block?

    2. Relevant equations

    3. The attempt at a solution
    I have no idea what I'm doing. I found the first part of the question, which was the change in kinetic energy.
  2. jcsd
  3. Jul 17, 2012 #2
    As you said, you already did the first part of this problem, wich is to find the change in kinetic energy (This isn't just a random question, you're gonna need this for the second part).

    The bullet leaves the block with less kinetic energy because of the work the block does. Since the bullet doesn't interact with anything else, then the change on it's kinetic energy has to be equal to the work done by the block.

    Now, with this, you should be abble to easily determine the work excerted by the block and you know the width of the block. Getting the average force should be pretty straight forward from there.
  4. Jul 17, 2012 #3
    Oh so you just use w/d= f? I think I got it.
  5. Jul 18, 2012 #4
    Precisely :D
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