posted by Will .
A uniform disk of mass 2kg and radius 10.0cm is spinning on a fixed frictionless bearing at 3 revolutions/second. A think cylindrical shell of mass 2kg and radius 10cm is carefully dropped onto the spinning disk so that they end up spinning together, with their edges coinciding.
a) How fast (in revolutions/second) are they spinning after the drop?
b) Is kinetic energy conserved is this process? If not, by what percentage has it changed?