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Homework Help: Bullets, block, and conservation of linear momentum

  1. Mar 25, 2012 #1
    I've been stuck on this problem and would really appreciate if someone could help me:

    A block of mass MB = 4.75 kg is initially at rest on a level rough surface for which the
    coefficient of kinetic friction is given by uk = 0.455 . Two bullets of equal mass
    Mb = 0.023 kg are moving horizontally in opposite directions with speeds related by
    v1 = (2 / 3)v2 = 324 m / s when they collide with the block simultaneously and become
    embedded in the block, as represented in the image below. Do the following:
    a) Calculate the speed of the block just after the collision. You may assume the
    conservation of mass during the collision.


    can someone please explain how to solve this in step by step detail? Or at least how to find the equation for the velocity just after collision?
  2. jcsd
  3. Mar 25, 2012 #2


    User Avatar

    Staff: Mentor

    Hi bphy, Welcome to Physics Forums.

    I'm afraid that we cannot solve this for you step by step -- that would be doing your homework for you, which is against the rules. What we can do is provide a hint or suggestion that you can use to get started. Show us the attempt you make as a result and then we can make further comments and suggestions.

    So to begin with, I'd suggest you investigate (in your text or notes) the concept of conservation of momentum for inelastic collisions.
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