Rewrite these equations properly: Both friction and centripetal acceleration point towards the center, so they must have the same sign. Pick a sign convention: For example, let towards the center be postive, away be negative. (Or vice versa; your choice.)Aki Yamaguchi said:1) T - umg = m R1 w^2
2) -T - umg = m R2 w^2
See what Cyclovenom did in post #22. Follow his lead.
To eliminate T, just add the two equations.