1. The problem statement, all variables and given/known data A small circular block of mass M traveling with a speed v on a frictionless table collides and sticks to the end of a thin rod of with length D and mass M. The picture shows a top down view of the block and rod on the frictionless table. What is the rod's angular velocity after the collision? Express your answer in some combination of M, v, and D. 2. Relevant equations conservation of angular momentum I_cm = M*D^2/12 I_point mass = Mr^2 3. The attempt at a solution So I guess the part that I'm struggling with is where to put the reference point. I tried the center of mass first: L_i = M*v*D/2 + I*omega and since omega_i = 0 its just L_i = M*v*D/2 L_f = omega(I_cm + I_point mass) = omega(M*D^2/12+M*D^2/4) and using conservation of angular momentum: M*v*D/2 = omega(M*D^2/12+M*D^2/4) M*v*D/2 = omega*M*D^2/3 omega = 3*v/(2*D) I tried the same thing with the upper end of the rod and got 3*v/(4*D) so I'm obviously doing something wrong. Do I have to include the translation of the center of mass? If I do I'm not quite sure how.