What best describes thermal expansion?

Thermal expansion refers to the physical phenomenon where a substance increases in volume as its temperature rises. When the temperature of a material increases, the kinetic energy of its particles also increases, causing them to move more vigorously and occupy a larger space. This process can be observed in various materials, including solids, liquids, and gases.

For example, when heating a metal, the atoms within it vibrate more intensely, pushing them further apart from each other and thus increasing the overall volume of the metal. Similarly, liquids expand and gases expand further upon heating, demonstrating this principle consistently across different states of matter.

This understanding is crucial in fields such as engineering and construction, where thermal expansion must be accounted for in the design of structures to prevent damage from temperature changes.