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

For the first problem, set up a differential equation for the acceleration along the rod: r'' = w^2*r (where r(t) is the distance from the axis of rotation at time t). Solve it, get rid of the arbitrary constants by setting known values (t=0->v=0, and t=0->r=r_0, where r_0 is small but nonzero). Then find t for r(t)=1.3, and then put that t into r'. As r_0 approaches 0, you'll get 1.56. Which turns out to be L*w, although I can't immediately see why...

I can't seem to visualize the second problem. What force is pressing the disk against the wall/floor?