A particle rotates in a circular orbit about a point located 30cm away, with angular speed 2 rad s^-1. If the angular momentum is 0.2 Js, determine the mass of the particle.

I used L=mr^2 omega and got 1.11kg

A constant torque of 0.2Nm accelerates the particle for 5s. Determine the final angular momentum of the particle. I'm not sure how to do this or which equation to use.