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Homework Help: Momentum and Impulse

  1. Jan 26, 2005 #1
    Hi there,
    i need to know if my approch to this question is right

    Particles A, B and C , each of mass m, lie at rest in a straight line in the order stated. A is projected directly towards B with velocity u. The coefficient of restitution is 0.5 in each impact that follows. Show that there will be three impacts in total and find the final velocities of each particle.

    working with a and b first
    work out momentum before mom = mu +0
    and momentum after mom = mv1 + mv2
    mu = m(v1 +v2)
    u = v1 +v2 {1}

    then using the equation velocity of separation = e x velocity of approach
    v2-v1 = e(u1-u2)
    v2-v1 = 0.5(u-0)
    v2-v1 = 0.5u {2}

    now adding {1} + {2} > v2=0.75u

    i would appreciate some advice on my technique/approch to this question

    thanks in advance
    Last edited: Jan 26, 2005
  2. jcsd
  3. Jan 26, 2005 #2


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    Homework Helper

    So how do you define the coefficient of restitution??


    P.S.Are u sure u don't need the KE equation??Though i think it is not conserved.
  4. Jan 26, 2005 #3
    i had question to ask,
    in the question it says "The coefficient of restitution is 0.5 in each impact that follows" does that mean e does not equal 0.5 for the contact between A and B
  5. Jan 26, 2005 #4
    The coefficient of restitution gives a measure of how elastic the collision is.
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