Suppose my system involves:
1) A mounted wheel with some outward flap
2) A bullet already in motion
Initially the net angular momentum is 0 and the net kinetic energy is just that of the speeding bullet.
The bullet hits the flap, causing the wheel to turn, and continues on (slightly slower).
Now the net angular momentum of the system is > 0 and the net kinetic energy is lower.
1) Is energy being converted into angular momentum here (so net energy is conserved)?
2) How is the net angular momentum of this system being conserved with the net amount before/after has changed?