How can the government of a nation invest in physical capital

By building highways, railways, and airports.

Explanation:

Physical capital is one of the three main factors of production according to economic theory. Physical capital refers to tangible, concrete, man-made goods that are used in the process of creating goods and services. Therefore, this can include items such as machinery, buildings, offices, vehicles, etc. One of the ways in which the government of a nation can invest in physical capital is by building highways, railways and airports, as these are physical goods that allow us to create other goods and services.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place