twisting moments at the ends

Question

The two shafts AB and BC, of equal length and diameters d and 2d, are made of the same material. They are joined at B through a shaft coupling, while the ends. A and C are built-in (cantilevered). A twisting moment T is applied to the coupling. If T_A and T_C represent the twisting moments at the ends A and C, respectively, then 

 

 

(a)$T_{C}=T_{A}$

(b) $T_{C}=8T_{A}$

(c) $T_{C}=16T_{A}$

(d) $T_{A}=16T_{C}$

Answer 1

Given two shafts of same length and dia d and 2d