What is a solid?

The video explains the characteristics of solids, which include having a fixed shape and volume. Solids only change shape when an external force is applied, such as heating or cutting. Unlike gases or liquids, solids have tightly packed molecules, making them incompressible. The video uses examples like a gold bar, a China teacup, and pizza dough to illustrate these properties. It emphasizes that while the shape of a solid can change, its volume remains constant unless consumed.

Explain the difference between solids, liquids, and gases in terms of molecular packing.

What is the only way to reduce the volume of pizza dough?