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Homework Help: Confermation on an answer

  1. Oct 20, 2004 #1
    two bullets of eqaul mass are shot at equal speeds at blocks of wood on a smooth ice rink. one bullet, made of rubber, bounces off the wood. the other bullet, made of aluminum, burrows into the wood. which bullet makes the wood move faster? why?

    i said the rubber bullet will make the wood move faster, because it will transfer almost of it intial momentum to the wood. can some one please tell me if i'm right or way off thanks.
  2. jcsd
  3. Oct 20, 2004 #2


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    It's the rubber bullet, and you seem to have the right idea, but I'm not sure that your explanation is very good.
  4. Oct 20, 2004 #3


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    Basically, youre right:
    The rubber bullet will not only transfer ALL it's initial momentum, it will also gain momentum in the opposite direction.
    Hence, the momentum of the block will be greater or equal than the initial momentum of the rubber bullet.

    The other bullet retains some of it initial momentum; hence, the resulting momentum of the block will be less than orequal to the initial momentum of the bullet..
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