[填空题]
(a) What is the anguxzj u.l (0khzbqyf2 .4m1 n,vsdw9 05b yg0xmqlar momentum of a 2.8-kg uniform cylindrical grinding wheel ofyq0b 50w9xd gm radius 18 cm when rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$