A solid brass rod of diameter $d=63mm$ has a steel sleeve with wall thickness $t=6mm$ solidly fused

onto it for reinforcement. What is the safe torque for the compound shaft if $G_s=84(10{)}^{4}k\frac{g}{c}{m}^2,$

$G_b=35(10{)}^{4}k\frac{g}{c}{m}^2,({}_w{)}_s=840k\frac{g}{c}{m}^2,({}_w{)}_b=525k\frac{g}{c}{m}^2.$ What is the ratio of this torque to that which

the brass rod alone could safely carry? $49,350kg-cm,1\mathrm{.}91$