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Homework Help: Ballistic Pendulum Speed

  1. Apr 21, 2008 #1
    A 12.5 g bullet is shot into a ballistic pendulum that has a mass of 2.37 kg. The pendulum rises a distance of 9.55 cm above its resting position. What was the speed of that bullet?
    m(bullet) = 0.0125 kg
    m(pendulum) = 2.37 kg
    h = 0.0955 m

    I know that I'm supposed to use conservation of energy:
    P(i)=P(f)
    m(1)v(i)=(m(1)+m(2))v(f)

    Unfortunately this equation does not take into account how high the pendulum swung, which is obviously an important factor.
     
  2. jcsd
  3. Apr 21, 2008 #2

    Doc Al

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    Staff: Mentor

    Treat this problem as having two parts:
    (1) The collision of bullet and pendulum. (What's conserved here?)
    (2) The swinging of pendulum+bullet after the collision. (What's conserved here?)
     
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