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Collision problem

  1. Oct 8, 2006 #1
    Collision problem UPDATED

    I messed up the first post. My cut/paste function malfunctioned. There should be sufficient information now. Sorry for the confusion.

    Two 500 g blocks of wood are 2.0 m apart on a frictionless table. A 10 g bullet is fired at the blocks. It passes all the way through the first block, then embeds itself in the second block. The speed of the first block immediately afterward is 6.0 m/s.

    What is the speed of the second block after the bullet stops?

    I tried to set this up as an inelastic collision problem, but the bullet passing throught he first block is throwing me off.

    I initiall set Pi=Pf but came up with a negative velocity way out of proportion for the bulet when exiting the first block. Where should I start with this problem?
    Last edited: Oct 9, 2006
  2. jcsd
  3. Oct 8, 2006 #2
    It would seem to me that there isn't sufficient information to solving this problem. Anyone else see something I'm missing??
  4. Oct 8, 2006 #3
    I guess the answer would be zero, but that assumes a completely ideal situation where the bullet comes out with the same momentum it went in with (i.e. no momentum is lost because there is minimal interaction). I don't know, otherwise there isn't really enough info.
  5. Oct 10, 2006 #4
    back to top with updated infor
  6. Oct 10, 2006 #5


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    Consider the first block+incoming bullet a SINGLE system.

    No external forces act upon this system.

    So, the momentum of this system is consserved throughout the collision period!

    What was the initial momentum of the system, and what soes it have to be equal to?

    Alternatively, regard both blocks+bullet a single system, and solve for the second block's final speed.
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