The correct answer is 20 rad/s^2. I need the work step by step with formulas, and derived formulas, with all unit conversions shown if necessary.

1.057 R m A mass m = 0.5 kg is hung from a pulley with moment of inertia / = 0.20 kg.m and radius R - 10 cm. There is friction in the pulley. The mass is dropped from rest, and after 2 s it traveled 4 m. What is the angular acceleration of the pulley? 2 rad/s2 5 rad/$2 10 rad/s- 20 rad/s2 40 rad/s