expansion process

Expansion is a process where a substance, such as a gas or metal, increases in size or volume when it is heated. When molecules gain energy from heat, they move more quickly and push outward, causing the material to expand. For example, in engines, metal parts like cylinders expand as they warm up, making precise measurements important. Similarly, hot air rises because it becomes less dense and takes up more space. This principle is important in engineering, climate science, and everyday applications, helping us understand how materials and environments respond to temperature changes.