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Homework Help: Impulse and Momentum Question

  1. Apr 18, 2010 #1
    When a ball of mass 180 g is struck by a bat moving in the opposite direction,
    the force acting on the ball is as shown in the graph (Figure 8.37). Determine
    The final velocity of the ball if it was initially moving at
    10.0 m s–1 south.

    The graph depicted the Impulse as 10Ns (I checked the textbook and it was right)

    However, when I calculated the final velocity, I got 65.55 and the answer in the textbook was 45.555

    Ft = m(v-u)
    10 = 0.180(v-10)
    65.55 = v

    Unless the Impulse is equation is Ft = m(u-v), i don't know how I got the answer wrong...
  2. jcsd
  3. Apr 18, 2010 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Since the ball and the bat are moving in opposite directions, the relative velocity is v+10 not v-10 as you have.
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