Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    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.

    Zz.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook