Rotational motion problems

Dear /sci/, I cannot for the life of me figure out how to do these two problems. If any kind person can provide a solution, please for the love of god make it as simple as possible since I'm retarded.

Love, Anonymous.

A smooth, thin rod, mass M=4.1 kg, and length L = 1.3 m, is spinning in a horizontal plane about a fixed vertical axis passing through one of its ends at an angular speed of w = 1.2 rad/s. A small ring of mass m = 0.010 kg, initially placed on the rod very close to the axis of rotation starts slowly sliding down the rod towards the other end of the rod. Calculate the speed of the ring when it reaches the other end of the rod

Anwser: 1.6

A homogeneous disk of radius R= 0.2m rotating at constant angular speed 21 rad/s about its central axis is carefully placed so that it simultaneously touches, both, a horizontal floor and a vertical wall. The coefficients of friction between the wall and the disk and the floor and the disk are the same mu = 0.05 . Calculate the angle, in degrees, the disk covers before stopping.

Answer: 1.6

The first problem, I see two possible solutions.

Soln a: v = angular velocity * L = 1.2 * 1.3 = 1.56

Soln b: This is more complicated. It uses two concepts, conservation of angular momentum and moment of inertia.
The moment of intertia (I) for the thin rod rotating on one end is I = 1/3 M L^2. The ring is simplified to be a point object, so I_ring = m r^2
Angular momentum (P) is moment of intertia times angular velocity. P = I w
conservation of angular momentum means intial angular moentum is going to be the same as the final.
For I_ring = m r^2, the r is 0 for the ring initially, it is L for the ring finally.

I w1 = Iw2 + I_ring w2
=> w2 = [M/(M+m)] w1

v = w2 L = 1.556

PS. you teacher is gay for making the answer with only 2 significant digits.