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Momentum questions

  1. Jun 13, 2013 #1
    1. The problem statement, all variables and given/known data

    34zx6l0.jpg

    2. Relevant equations

    Mg deltha H

    1/2mv^2

    p=mv


    3. The attempt at a solution

    I believe statement to do with the Gravitational energy is correct, considering the equation I listed. I would have to agree with statement 2 since gpe=ke


    Here is what I am thinking, I disagree with the Ke = the same as before collision.

    my reason is 1/2mv^2= 0.16j ----- v= sqrt (0.32/71.6ex-3) now if this is correct we can work out the momentum

    which i have down as 1.5 x10^-1 using, momentum is conserved we can work out velocity of the pellet which turns out to be 180m/s (I think this could be wrong)

    But could I just say that, the collision was inelastic, hence kinetic energy is not conserved, therefore working out velocity from Momentum would be better since momentum is conserved.
     
    Last edited: Jun 13, 2013
  2. jcsd
  3. Jun 13, 2013 #2

    jedishrfu

    Staff: Mentor

    This is a terribly formatted post can you clean it up a bit and make sure your equations are correct and readable?
     
  4. Jun 13, 2013 #3
    done
     
  5. Jun 13, 2013 #4
    anyone help?
     
  6. Jun 13, 2013 #5

    haruspex

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    Good answer.
     
  7. Jun 14, 2013 #6
    Are you being serious or troll? I can't tell :cry:

    If you could outline what is actually good and makes sense in my answer would make me more confident.
     
  8. Jun 14, 2013 #7

    berkeman

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    haruspex is most definetly not a troll -- he is one of our very valued Homework Helpers and Science Advisors. :smile:
     
  9. Jun 14, 2013 #8

    haruspex

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    I was being quite serious :smile:. You correctly identified the flaw in the student's reasoning, and that the correct way is to use conservation of momentum.
     
  10. Jun 14, 2013 #9
    but doesn't 180m/s seem to big of a value for the velocity.
     
  11. Jun 14, 2013 #10

    haruspex

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    No, it looks right to me. Remember that the pellet is only 1/90 of the mass of the ball.
     
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