Physics Rotational Mechanics Level: High School

A particle of mass M is moving on a frictionless horizontal table and is attached to a massless string whose other end passes through a hole in the table where I am holding it . Initially particle is moving in a circular of radius r_0 with angular velocity w_0 but I now pull the string down through the hole until a length r remains between the hole and particle , What is the particle angular velocity now ?

Assume that I pull the string so slowly that we can approximate the particles path by a circle of slowly shrinking radius , calculate the work I did pulling the string and compare this answer with the particles gain in Kinetic energy ?