r1+r2=L,m1r1=m2r2,把r2=L-r1代入m1r1=m2r2得r1=m2L/m2+m1

更新时间2018-07-15 12:58:23

我怎么算不出？求详细过程解：m1r1=m2r2
m1r1=m2(L-r1)
m1r1+m2r1=m2L
(m1+m2)r1=m2L
r1=m2L/(m1+m2)