1. The problem statement, all variables and given/known data A disk of mass m1 is rotating freely with constant angular speed ω. Another disk of mass m2 that has the same radius is gently placed on the first disk. If the surfaces in contact are rough so that there is no slipping between the disks, what is the fractional decrease in the kinetic energy of the system? (Use any variable or symbol stated above as necessary. Enter the magnitude.) It wants ΔK/Ki 3. The attempt at a solution I really don't think I understand what is being asked of me here. I have attempted to find ΔK by using the moment of inertia of a disk, and then adding a second disk of mass m2. But that got me nowhere. I wish I could offer up a better attempt but I'm at a loss.