Gas Pressure
Gas Pressure is the push that trapped gas makes against the walls of its container, like the force that launches a film canister rocket.
When you pump air into a bicycle tire, the air molecules bounce around inside and push against the rubber walls. The more air you add, the harder they push. That push is gas pressure — the same force that makes a balloon stretch tight when you blow it up.
Explaining gas pressure by grade level
Think about a film canister rocket. You mix baking soda and vinegar inside the canister and snap the lid on. The mix makes a gas that fills up the space. The gas pushes harder and harder on the lid until — pop — the lid flies off and the canister shoots up. That pushing is gas pressure.
Projects that explore gas pressure
Gas pressure is the push that trapped gas makes against the walls of its container. When vinegar reacts with baking soda inside a sealed film canister, carbon dioxide gas fills the space. Pressure rises fast. The lid blows off and the canister shoots upward.
Trapped gas pushes against whatever holds it in. Dry ice is frozen carbon dioxide that does not melt at normal air pressure — instead it sublimates, changing directly from solid to gas. Drop a pellet into a balloon and tie it shut. As the dry ice becomes gas, it pushes outward against the rubber walls and the balloon inflates.