Equation Icon  { } a a 1 [ b] a 1 2 a 1 2 a b 1 2 a b c 3 sω = r Ω − -r 1 − rab(u )Ω a (u) − -r a˙(u ) −--r R 0b0(u )Ω + -r R b0c(u)Ω Ω + O(r )(11.2 ) 2 6 6 3