[填空题]
(a) What is the angular momentumj5anuj3ckm (- of a 2.8-kg uniform cylindrical grinding wh geek e-n:ujd;e06g/heel of radius 18 cg6 /; -ej0hd:eeukengm when rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$