[填空题]
(a) What is the angular *e:9b6i t u; jjjap8zmmomentum of a 2.8-et l s *;zog)/igr::rbkg uniform cylindrical grinding wheel of radius 18 cm whensrez* r: )gigtb;lo:/ rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$