(Solved): *4-72. The two cylindrical rod segments are fixed to the rigid walls such that there is a gap of \ ...

*4-72. The two cylindrical rod segments are fixed to the rigid walls such that there is a gap of \( 0.01 \) in. between them when \( T_{1}=60^{\circ} \mathrm{F} \). Each rod has a diameter of \( 1.25 \) in. Determine the average normal stress in each rod if \( T_{2}=400^{\circ} \mathrm{F} \), and also calculate the new length of the aluminum segment. Take \( \alpha_{\mathrm{al}}=13\left(10^{-6}\right) /{ }^{\circ} \mathrm{F}, E_{\mathrm{al}}=10\left(10^{3}\right) \mathrm{ksi} \), \( \left(\sigma_{Y}\right)_{\mathrm{al}}=40 \mathrm{ksi}, \alpha_{\mathrm{cu}}=9.4\left(10^{-6}\right) /{ }^{\circ} \mathrm{F},\left(\sigma_{Y}\right)_{\mathrm{cu}}=50 \mathrm{ksi} \), and \( E_{\mathrm{cu}}=15\left(10^{3}\right) \mathrm{ksi} \)