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Homework Help: Bullet fired in a pendulum. Calculate the initial speed of the bullet.

  1. Oct 20, 2005 #1
    I've been trying to figure this out for a while and it's due tomorrow...any help would be greatly appreciated.

    A .005 kg bullet is fired into a 4.0 kg pendulum bob initially at rest and becomes embedded in it. If the pendulum rises a vertical distance of 5.0 cm, calculate the initial speed of the bullet.

    I tried to use a kinematics equation to find the velocity, but I needed an acceleration, so I tried to use F=ma, but I'm retarded or something but couldn't figure it out any way. Thanks for any help offered.
  2. jcsd
  3. Oct 20, 2005 #2


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    1. Use conservation of momentum when the bullet hits the pendulum.

    2. Then use conservation of energy when the bullet+pendulum swing to the top.

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