[填空题]
(a) What is the angu(d4 hcr5 m7othxb 7p0w1jk k8omwzbhv4 t1 7+4x;umuilar momentum of a 2.8-kg uniform cylindrical grinding wheel of radius 18 cm when 4o1k8j;uki17x+ bwvm tu4mhz rotating at 1500 rpm? $kg \cdot m^2$ (b) How much torque is required to stop it in 6.0 s? $m \cdot N$