[填空题]
(a) What is the angular momentum of a )qd; )x.lzmr 4cx/chjg *az9 ,- lzgpho 4o4hh2.8-k)7:l2 ri/i:8(u w ssfrmbgzebg uniform cylindrical grinding wheel of radius 18 cm when rotating at sgm/8()wb bz r ifs7ul:ei:2r1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$