The only thing wrong with your answer seems to be (r1)(f)(t)=I1(w1-w0) it should be I1(w0-w1) because if you write it as you have written here you should write it with a negative sign... Otherwise it seems fine... Your final answer will be in terms of the MOI which would be m(r^2)/2 if the...
The centre of mass of the system of particles has a velocity given by [(m1)(v1)+(m2)(v2)]/(m1+m2). Here v1 and v2 are the respective velocities and not just speeds. You start seeing the two pucks in the centre of mass frame. Minimum separation will be attained when the velocity of both the pucks...