1. The problem statement, all variables and given/known data A particle of mass M moving on a frictionless surface with velocity ##V_0## collides totally inelastically with an uniform vertical rod of mass M and length L. After immediately the collision, what is the center-of-mass velocity, the moment of inertia about the center-of-mass, and the angular speed of the system. 2. Relevant equations conservation of momentum and conservation of angular momentum moment of inertia 3. The attempt at a solution I am wondering what point does the particle+rod system will rotate about?