${}_1={16\mathrm{.}10}^{-6}$

$\frac{1}{C^O}$

${}_2={12\mathrm{.}10}^{-6}\frac{1}{C^O}$

$E_1=100$GPa

$E_2=200$GPa

${}_{ss,1}=100$MPa

${}_{ss,2}=150$MPa

In the figure given, a circular cross$-$section rod with a diameter of $4cm,$ made of material number $1,$ is placed inside the pipe produced from material number $2.$ The entire system is mounted on a rigid plate from below and on a fixed wall from above. The temperature when the system is installed is $10C.$ How much should the temperature be changed to close the $19cm$ gap?