Answers
r1=0.138m, r2=0.138+0.0870 = 0.225m
Let us find r3 now,
Use cosine law in the triangle in the figure above,
Φ=180-55.7=124.3 deg
r3^2=r1^2+r2^2-2*r1*r2*cosΦ
r3^2=0.138^2*0.225^2-2*0.138*0.225*cos124.3
r3=0.1896m
Moment of inertia of a disk = 1/2mr^2
Moment of inertia of disk A about its center = IA=1/2*mA*r1^2 =1/2*0.566*0.138^2 = 0.005389 kg*m^2
By parallel axis theorem,
Moment of inertia of disk A about point p = IAP= IA + mA*r1’^2 = 0.005389 + 0.566*0.138^2 = 0.01617 kg*m^2
Moment of inertia of disk B about its center = IB=1/2*mB*r2’^2 =1/2*0.245*0.0.0870^2 = 0.0009272
By parallel axis theorem,
Moment of inertia of disk A about point p = IBP= IB + mB*r3’^2 = 0.0009272+ 0.245*0.225^2 =
0.01333kg*m^2
Moment of inertia of both disks about point p = IAP+ IBP= 0.01617+ 0.01333 = 0.0295 kg*m^2