Question

why are iron bridges mounted on steel rollers

Answer 1

It is because there is always an expansion between the iron materials because of the high pressure . And if it will expand, there's a chance that the bridge may collapse.

Hope this helps!!!

Answer 2

Explanation:

iron bridges are mounted on steel rollers because it expand on heating and contract on cooling.so ,leaving a small space in between for the expansion and contraction. Thus ,the bridge is saved from collapse. In a construction of a bridge, Steel girders are used.