1. The problem statement, all variables and given/known data A wooden block of mass M resting on a frictionless, horizontal surface is attached to a rigid rod of length l and of negligible mass. The rod is pivoted at the other end. A bullet of mass m travelling parallel to the horizontal surface and perpendicular to the rod with speed v hits the block and becomes embedded in it. a.) What is the angular momentum of the bullet-block system about a vertical axis through the pivot. 2. Relevant equations L=r x p 3. The attempt at a solution So I got L initial, which is mvl and L final which is (m+M)vfl. What I thought the angular momentum would be would be L final - L initial, but the answer is apparently mvl down, which is just the bullet. Where did I go wrong?