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Momentum and collisions

  1. Oct 19, 2012 #1
    if a hard sticky mud ball is trown on a wall it sticks to it
    it is an inelastic collision
    K.E. is not conserved
    but here momentum is also not conserved because mud had an initial velocity
    so initial momentum of mud + initial momentum of wall (that is 0) = initial momentum of mud
    final momentum of mud (that is 0 or less than its initial momentum)+final momentum of wall= 0 or less than total initial momentum
    please explain hiw momentum is conserved here??
     
  2. jcsd
  3. Oct 19, 2012 #2
    The wall/mud combination does have a small final velocity. If the wall is attached to a planet, this velocity is tiny, since the mass is huge.
     
  4. Oct 19, 2012 #3

    mfb

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    Momentum is conserved - but if the wall is attached to the ground, you have to consider the momentum of the whole earth, which changes at the impact. The mass of earth is huge, so you won't be able to measure it.

    Edit: Too slow :(
     
  5. Oct 19, 2012 #4
    will the stiky mud also have a final velocity??
     
  6. Oct 19, 2012 #5

    mfb

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    The same as the wall and earth, probably.
     
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