Irodov Problem 1.190

As seen from the rotating frame of reference, the disc will not only be moving outwards with a velocity v0 but also will be rotating with an angular velocity w in the opposite direction. In other words, from the point of view of an observer on the rotating frame, it will seem as though the disc is rotating with an angular velocity w while the radius of rotation increases with time as v0t. The tangential velocity of the disc at some instant of time will be wv0t. Hence the angular momentum as function of time is thus given by,