Question

Bridges are mounted on ______ to allow for expansion and contraction.

Answer 1

1. The most common change caused by heat is expansion.
2. Matter increases in volume when there is an increase in temperature and if the temperature is reduced volume decreases.
3. Due to the presence of rollers, iron girders used in bridges can easily expand or contract and it prevents cracking during the summer and winter seasons.

Hence, bridges are mounted on rollers to allow for expansion and contraction.