1. The problem statement, all variables and given/known data A bullet of mass 10.0 g is fired into a ballistic pendulum of mass 3.00 kg. The pendulum swings back and rises 12.0 cm. Find the original speed of the bullet. 2. Relevant equations p1 + p2 = p1' + p2' We're learning momentum right now, and I think that's what I need. 3. The attempt at a solution I'm too confused to even write much down. I've only thought about it. If the string's length isn't given, how can I solve this? If a string was 50000 meters long and someone hit it, wouldn't it swing less than a string 10 meters long? It would travel a different distance along the circumference with differing string lengths, right?I wrote this down and can't go any further: .5 * .01 * v^2 = 9.8 * .12 * 3.01(wrong answer for v) The only way I could write anything down was using energy, but that's not what this chapter is about :(. I don't even mind if you don't solve it all the way; a step in the right direction would be appreciated. I should have posted this in introductory physics. Sorry, I was in a rush.