A merry-go-round rotates at the rate of 0.15 rev/s with an 85-kg man standing at a point 2.0 m from the axis o?

A merry-go-round rotates at the rate of 0.15 rev/s with an 85-kg man standing at a point 2.0 m from the axis of rotation. The new angular speed when the man walks to a point 0.6 m from the center is 4.6 rad/sec knowing that the merry-go-round is a solid 25-kg cylinder of radius 2.0 m. Calculate the change in kinetic energy due to this movement.