Lag1989 problem 4.47

The horizontal platform in the form of a homogeneous disk of radius R = 1.2 m rotates with a frequency n₁ = 4.5 rpm. At the edge of the platform is a man weighing m = 60 kg. How often will the platform rotate if a person moves to the center? The moment of inertia of the platform J = 144 kg ּ · m²; a person can be mistaken for a material point.