[填空题]
(a) What is the angular momentum os)gpnh:6:wp5 2z mx5ad*z we yf 7n*,mxtefvnv3a a *a( a 2.8-kg uniform cylindrical grinding wheel of radius 18 cma3,v am7naf(t*exn v* when rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$