Question

The two rotating spheres shown in the figure have different masses andmoments of inertia. They move toward each other until they touch briefly.Since there is friction, their angular velocities change as a result of the contact.Assuming the spheres interact only among themselves, the total angular
momentum of the system after they separate
(A) is larger than before they came into contact
(B) is the same than before they came into contact
(C) is smaller than before they came into contact
(D) may be smaller or larger than before they came into contact, depending on how fast they are
spinnin

Answer 1

We have discussed this here. Clearly the friction can cause both to slow down in some geometries, and friction is energy lost as heat, so the angular momentum decreases. C