Thermal Expansion Meaning
An increase in the size of a substance when it is heated. Thermal expansion. When materials are heated, they expand because their particles move faster and spread apart.
An increase in the size of a substance when it is heated. Thermal expansion. When materials are heated, they expand because their particles move faster and spread apart.

Imagine trying to squeeze into your favorite pair of jeans after a big holiday meal. Just like how your jeans feel tighter when you're full, materials expand when they heat up. In both cases, whether it's your waistband or a metal rod, adding energy (from food or heat) causes an increase in size, as molecules move apart to make room, making it a perfect analogy for thermal expansion.

