1. The problem statement, all variables and given/known data A disk of mass M1 = 350 g and radius R1 = 10 cm rotates about its symmetry axis at f_initial = 152 rpm. A second disk of mass M2 = 258 g and radius R2 = 5 cm, initially not rotating, is dropped on top of the first. Frictional forces act to bring the two disks to a common rotational speed f_final. a) What is f_final? Please give your answer in units of rpm, but do not enter the units 2. Relevant equations T = I*a I = (m*r2)/2 3. The attempt at a solution I found the moment of inertia of M1 I = (.5)(.35)(.12) = .00175 kg*m2 M2 I = (.5)(.258)(.052) = .0003225 kg*m2 I found the angular velocity [tex]\omega[/tex] 152rpm = 304pi rads/min = 5.06pi rads/sec I don't suppose that I can just consider the mass to have just increased can I, because it specifies friction. I know some numbers, but how to put them together?