Thermal Expansion

Real World Example

Imagine trying to fit more clothes into an already packed suitcase when you're heading on a trip. Just like the suitcase becomes more crowded and may even bulge as you add more clothes, substances expand when heated because their particles move more vigorously and need more space. In both cases, whether it's clothes in a suitcase or particles in a substance, adding more energy (clothes or heat) causes an increase in space and volume.