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Homework Help: Trolley Momentum Question

  1. Apr 24, 2010 #1
    A man of mass 80kg (m1) stands on a trolley of mass 120kg (m2) and throws a parcel of mass 10kg (m3) with a velocity of 4.0ms-2 (u2) horizontally away from the rear of the trolley. What is the speed with which the trolley and the man commence to move?

    I am just wondering whether the initial velocity of the man and the trolley is zero? I can only seem to work out the correct answer if it is zero because I can't solve for two variables.

    (m1+m2)u + m3u2 = (m1+m2)v

    200 x 0 + 40 = 200v
    40 = 200v
    0.2ms-1 = v
  2. jcsd
  3. Apr 24, 2010 #2


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    Homework Helper

    The initial velocity is assumed to be 0, yes.
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