A circle plate frictionlessly rotates about a hori...

A circle plate frictionlessly rotates about a horizontal axis that passes through the center of the plate. As shown in Fig. two bullets with the same mass shoot into the plate in the opposite direciton on one straight line with the same magnitude of the velocity, and stop inside the plate. At the moment the two bullets shoot into the plate, if the angular momentum of the system of the plate and two bullets is L and the angular velocity is w, then we have ().

A、L remains unchanged, w increases;

B、Both L and w remain unchanged;

C、L remains unchanged, w decreases;

D、Both L and w are uncertian.