Pressure cookers raise the boiling point of water so food cooks faster than usual.

The longer version

Sealing a pot traps the vapour rising from the liquid, so pressure builds inside. Boiling begins only when the vapour pressure matches the pressure above the liquid, so with more pressure the water must get hotter before it bubbles. That higher temperature speeds up the chemical and physical changes that soften food.

Steam also penetrates dense material more effectively than dry heat, helping toughness break down. Because the boiling point climbs with pressure, the same meal finishes in much less time than in an open pan. Releasing the pressure restores the normal boiling point, and the trapped heat escapes violently.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.