$4.)(10)$ A solid copper rod and an aluminum tube are both fixed to rigid walls such that there is a gap of $0\mathrm{.}096$ in $.$ between them when $T=70\mathrm{.}0F.$ Both have an outside diameter of $1\mathrm{.}25$ in$.,$ the tube has an inside radius of $\mathrm{.}25$ in $.$

Materials: C$14500$ Cu $-$ hard and $2014-$T$4$ Al

a$)(4)$ Calculate the temperature when they just touch. Both are heated to the same temperature.

b$)(3)$ Find the stress in the rod and tube if the temperature is increased to $260F.$

c$)(3)$ Determine the highest temperature they can be raised to without causing yielding in either mat

For b$)$ and c$)$ a