Same Stuff, Different Forms

Did you know that many of the things you may see or use every day—such as the water in a glass, the air in a football, and even the hard metal in a toy car—are potential shape-shifters?

The substances that these things are made of can have the form of a solid, a liquid, or a gas. The form they take depends mostly on their temperature. When water gets cold enough, it becomes a hard solid we call “ice.” When it gets hot enough, it becomes a wispy gas we call “steam.” Many other substances behave the same way when they are heated or cooled enough.

A solid holds its own size and shape without needing a container. If you pour water into an ice tray and freeze it, the water will keep the shape of the cube-shaped molds in the tray. You can think of the solid metal in a toy car as frozen too, but its melting temperature is much higher than the temperatures we live in. The person who made the car poured very hot liquid metal into a car-shaped mold and let it cool down and freeze.

A liquid does not hold its own shape. If you pour a measuring cup of water into a tall glass or a shallow bowl, it will take the shape of its container. But that water does keep its own size. It measures one cup. Everyday liquids such as milk, paint, and gasoline act this same way.

Gases do not keep their own shape or their own size. When air is pumped into a football, it takes the shape and size of the ball. As more air is pumped in, the ball gets harder but not much bigger. The air changes its size to fit the space inside the ball. []

Aceh, Indonesia

5th April 2016

TM. Noumi