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: Finding speed

  1. Dec 21, 2009 #1
    1. The problem statement, all variables and given/known data

    An 8 kg bullet is fired into a stationary 9 kg block of wood which is free to move. The bullet is stopped in the wood which has a velocity of 40 cm/s after the impact. What was the speed of the bullet?

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 21, 2009 #2
    use the conservation of momentum
     
  4. Dec 21, 2009 #3
    Well we know from the question that the bullet gets lodged into the wood upon impact. What kind of collision would that be? Elastic or Inelastic? What kind of properties, specifically with conservation of momentum/kinetic energy does that collision contain?

    Let me know if you need more help.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook