Using ${}_{\text{a}\text{l}\text{l}}=40$MPa, determine the largest torque that may be applied to each of the brass bars and to the brass tube shown. Note that the two solid bars have the same cross$-$sectional area, and that the square bar and square tube have the same outside dimensions.

Fig. Q$7$

Ans: $T_1=532N*m,T_2=414N*m,T_3=555N*m$