Rotational Motion Part 1

Two Coaxial discs, having moments of inertia I1 and

I1

2

are rotating with respective angular velocity ω1 and

ω1

2

, about their common axis.They are brought in contact with each other and thereafter they rotate with a common angular velocity. If Ef and Ei, are the final and initial total energies, then (Ef−Ei) is