How Does Impact Affect System Angular Momentum?

[fball558]

system angular momentum??

Homework Statement

A rotating uniform-density disk of radius 0.9 m is mounted in the vertical plane. The axle is held up by supports that are not shown, and the disk is free to rotate on the nearly frictionless axle. The disk has mass 3.6 kg. A lump of clay with mass 0.6 kg falls and sticks to the outer edge of the wheel at the location < -0.585, 0.684, 0 > m. Just before the impact the clay has a speed 9 m/s, and the disk is rotating clockwise with angular speed 0.65 radians/s.


(a) Just before the impact, what is the angular momentum of the combined system of wheel plus clay about the center C? (As usual, x is to the right, y is up, and z is out of the screen, toward you.)


(b) Just after the impact, what is the angular momentum of the combined system of wheel plus clay about the center C?

The Attempt at a Solution

I said clay ball has momentum only in the y direction. it is falling at 9 m/s and has mass .6 kg so .6 * 9 = 5.4 since it is falling i believe this would be negative.
now I am stuck on the disk. how do i find the x and y component??

 

[fball558]

for the disk would the z component be found by
L = wI where L is angular momentum??
i do this and get 28.187
does this sound right??