# Angular momentum multiparticle system

1. Nov 8, 2007

### solrac214

1. 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 0.4 kg falls and sticks to the outer edge of the wheel at the location < -0.81, 0.392, 0 > m. Just before the impact the clay has a speed 9 m/s, and the disk is rotating clockwise with angular speed 1.00 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?

2. L = Ltrans + Lrot
L = r x p
L = |r||p|sin(theta)
moment of inertia of a disk = (1/2)mr^2

3. Ok so i tried solving this by finding out the angular momentum of the disc which is <0,0,-1.458> but I cannot figure out the total before the impact. I don't think I solve this without the angle of impact but there has to be a solution. i think that afterwards the angular momentum of both will just be the same as the moment before the impact because momentum is conserved right?

2. Nov 8, 2007

### solrac214

i figured out that the direction is in the negative y cause the clay falls on the disc but i still can't figure out either before or after the impact momentum

3. Nov 8, 2007

### solrac214

figured out the momentum after the impact <0,0,1.458> still clueless about before the impact