[填空题]
(a) What is the angular momentum of a-, ge3a;4k dq:ocjun v 2.8-kg uniforsg,rx b9qvag2 bel, k6cgr+3: m cylindrical grinding wheel of radgg93 k2e,brgblc,:+qvx as r6ius 18 cm when rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$