[填空题]
(a) What is the angular momentum of a 2.8-kg uniformclrz2v rv.(hi6 bmt-018mi yb gj(v* 8xits6i cylindrical grinding wheel of radius 18 cm when rotatii6t 8 ig*vxj(sng at 1500 rpm? $kg \cdot m^2$
(b) How much torque is required to stop it in 6.0 s? $m \cdot N$
