[填空题]
(a) What is the angular momentum of a 2.8-kg uniform cylindrical grindio qlas+: fz:c4yz8v u3ng g eceqn7xur- ey;( p1iv3eh 51wheel ofyng ( e51cq1e- ih7r;pxu3ve e radius 18 cm when rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$