1. The problem statement, all variables and given/known data A smooth hoop of mass M with 2 beads of mass m each hangs from the ceiling. at t=0 the beads are released from the top and they start sliding down. What is the mass range M/m for the ring to rise as the beads fall. 2. Relevant equations Friction force: ##f=mg\mu## 3. The attempt at a solution I don't see how the normal forces can raise the ring. when on the upper or lower half of the ring the normal forces pull down the ring. and that's before i consider linear momentum or anything else.