Question regarding conservation of angular momentum

[ustudent]

Let's say I had a disk sitting at rest and I threw a ball of clay toward the edge of the disk, causing the clay to stick to the disc and having both rotate as a result. If the wheel's axle had friction and would eventually slow the disc down, can you still say that angular momentum is conserved just before and just after the collision (similar to impulse approximation for linear momentum)? Thanks.

 

[xts]

Sure. You just must consider a system consisting not only of your disk and blob of clay, but also of you and whole Earth, as you change Earth angular momentum as you throw, and friction transmits the momentum between disk and Earth.