An aluminium and steel rods having same lengths and cross-sections are joined to make total length of 120 cm at 30°C. The coefficient of linear…

An aluminium and steel rods having same lengths and cross-sections are joined to make total length of $\displaystyle 120$ cm at $\displaystyle 30$°C. The coefficient of linear expansion of aluminium and steel are $\displaystyle 24 \times 10^{-6} /{ }^{\circ} \mathrm{C}$ and $\displaystyle 1.2 \times 10^{-5} /{ }^{\circ} \mathrm{C}$, respectively. The length of this composite rod when its temperature is raised to $\displaystyle 100^{\circ} \mathrm{C}$, is $\displaystyle \_\_\_\_$ cm.