[填空题]
(a) What is the angular momentum of a 2.8-g gsb-v bq)*l2kg uniform cylindrical grindin 3unidynrbcy7,(4:a+ z6 wqryg wheel of radius 18 cm when rotating at y7 ad 6n34 urn (:yqbr+yicw,z1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$