Angular Momentum and stuff

A particle of mass m is attached to the end of a light string of length L. The other end of the string is passed through a small hole, and is slowly pulled through it. The particle is origionally spinning arround the hole with angular velocity w. Find the angular velocity when the length of the string has been reduced to L/2. Find also the tension in the string when its length is r, and verify that the increase in kinetic energy is equal to the work done by the force pulling the string through the hole. (Neglect gravity).

Any help will be gratefully recieved.

Read your fucking textbook.

Fucking read your textbook.

Well, you misspelled received. Hope that helps.