1. The problem statement, all variables and given/known data We have a bead sliding with friction on a hoop oriented vertically. First the hoop rotates about its center with rotation axis perpendicular to its plane. Second, the hoop rotates about a vertical axis as well. In both of these cases, are the constraints holonomic or nonholonomic? Are the time dependent or independent? I think in both cases the constraints will be time-dependent. I am confused as to whether or not they will be holonomic / non-holonomic. I thought they would both be non-holonomic since friction is involved. Is this right?