# Do linear expansion, area expansion, cubical expansion all occur simultaneously in a metal rod when heated?

Consider a metal rod being heated. As metal rod is a good conductor, it spreads heat all through it. If so I think all the linear,area and cubical expansion takes place simultaneously practically. Am I right?

• It's very broad question, it actually depends on type of metal and it's characteristics, while volume expansion is always accompanied by linear or aerial or both. Jan 4 at 9:17
• It really depends on the material and on the constraints of the system: as an example, if the medium is contained between two parallel rigid walls there could be no area expansion in the direction perpendicular to those walls (for small $\Delta T$). In this example, thermal expansion is opposed by a stress state of compression, produced by the constraints Jan 4 at 9:26

• false. Even with a linear non-isotropic medium, strain as a function of temperature needs a tensor relation $\varepsilon \hspace{-4pt} \varepsilon = \alpha \hspace{-5.5pt} \alpha \Delta T$. And you're not even considering constraints and stress fields $\sigma \hspace{-4.5pt} \sigma$ Jan 5 at 0:08