n=0,B g 21(转动定律的瞬时性) 3—4 mL2 L mg B6=g/3 (M,B随时间变吗?) 2 4.4=6mS;a,=1800m/ 2 三.计算题 1.解:(1)O0=2zn=2z 500 52.36rad/s 60 3000 O(5)=2nn=2=314.16rad/s 60 314.16-52.36 (2)B= =52.36rad/s2 p=00t+Bt2=5236×5+5236×5=9163rad 146r/s 2丌1． 0  = 0, 0 3 2 g l  = （转动定律的瞬时性） 2. 3 2 4 I mL = ; 0 1 4 M mgL = ; 0  = g L / 3 （M, β随时间变吗？） 1． 0 3 2 v l  = 4. 2 a m S 6 /  = ; 2 1800 / n a m S = 三. 计算题 1.解：(1) 0 0 500 2 2 52.36 / 60    = =  = n rad s 3000 (5) 2 2 314.16 / 60    = = = n rad s (2) 0 314.16 52.36 2 52.36 / 5 rad s t    − − = = = (3) 2 2 0 1 1 52.36 5 52.36 5 916.3 2 2    = + =  +  = t t rad 146 / 2 n r s   = =