Inertia for a special yo-yo help!!! 1. The problem statement, all variables and given/known data A yo-yo is made of two solid cylindrical disks, each of mass M and diameter D, , joined by a (concentric) thin solid cylindrical hub of mass m and diameter d. Use conservation of energy to calculate the linear speed of the yo-yo just before it reaches the end of its long string length L, if it is released from rest. 2. Relevant equations KE for translational: 0.5*m*v^2 KE for rotational: 0.5*I*w^2 PE: mgh for this problem: potential = KE(trans) + KE(rot) 3. The attempt at a solution My main concern is how to treat the inertias for the 3 cylindrical objects (2 identical big cylindrical disks and 1 small cylindrical hub). At first I tried to simply combine the inertias for all 3 into one KE equation (i.e. I = all 3 cylindrical objects...KE(rot) = .5*I*w^2.) but when I tried to convert the w to v/r I couldnt decide which r to use (disk or hub). So then I tried to separate the KE(rot) into 2 (1 for hub, 1 for 2 disks). this way allowed me to have different r for the w=v/r substitution, but my answers came out wrong. How then should I do this problem?