--- title: Pressure tricks: pumps, tyres and vacuums — a lesson of Mova's school · trees and pragmatics description: «Pressure tricks: pumps, tyres and vacuums», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Air always moves from where it is squashed and presses harder to where it presses less, and many machines in your home are cleve --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/) / Pressure tricks: pumps, tyres and vacu… # Pressure tricks: pumps, tyres and vacuums Lesson 16 of the physics course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/physics/16-pressure-tricks-pumps-tyres-vacuums/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/0/) — Air always moves from where it is squashed and presses harder to where it presses less, and many machines in your home are clever ways of using that one rule. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/1/) — A vacuum cleaner does not really suck: its fan throws air out of the back, the pressure inside drops, and the outside air rushes in at the nozzle, carrying the crumbs with it. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/2/) — When you breathe in, a muscle under your lungs pulls down and makes more room, the pressure in your lungs drops, and the air outside pushes in, just like water into a syringe when you pull the plunger. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/3/) — Warmth changes pressure too: a warm gas pushes harder, a cold one pushes less, so a balloon in the freezer shrinks and a jar sealed hot pulls its lid in as it cools. - [4](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/4/) — Water also cares about pressure: under a heavy lid it can get hotter than 100 degrees before boiling, and on a high mountain it boils before it gets that hot. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/5/) — A vacuum cleaner's fan pushes air out, which lowers the pressure inside, so the outside air pushes in at the nozzle carrying dust. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/6/) — A punctured tyre goes flat because the squashed air inside escapes through the hole to the lower pressure outside. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/7/) — In soapy water the air escaping from a punctured tube makes bubbles that show where the hole is. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/8/) — Squeezing a ketchup bottle raises the pressure inside, and a push on a closed bottle spreads to every part, so the sauce is pushed out of the hole; when you let go, the bottle springs back and outside air is pushed in with a gurgle. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/9/) — Pulling back a syringe's plunger makes more room inside, the pressure drops, and the outside air pushes water in. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/10/) — When you breathe in, a muscle under your lungs pulls down, your chest gets bigger, the pressure inside drops, and outside air pushes in. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/11/) — A fizzy drink has gas squashed into it under high pressure, and when you open it the pressure drops and the gas escapes as bubbles with a hiss; if the bottle was shaken first, the gas rushes out all at once and sprays everywhere. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/12/) — A pressure cooker traps steam so the pressure rises and water boils at a higher temperature, which cooks food faster; it has a safety valve and only grown-ups use it. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/13/) — On a high mountain the air presses less, so water boils below 100 degrees and pasta and eggs take longer to cook. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/14/) — A balloon shrinks in the freezer and grows again when warmed, because cold air pushes less on the rubber. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/15/) — A jar closed while hot has a lid held down by the outside air once it cools, and the lid pops as air rushes in when you open it. - [16](https://md.mova.elamur.ai/free/en/corpora/school/physics/16-pressure-tricks-pumps-tyres-vacuums/16/) — If the safety button on a new jar lid is already up in the shop, the seal may be broken and the food may be bad. - ← previous: [Wind and weather](https://md.mova.elamur.ai/free/en/corpora/school/physics/15-wind-and-weather/) - next →: [What sound is: wobbles in the air](https://md.mova.elamur.ai/free/en/corpora/school/physics/17-what-sound-is-wobbles-in-the-air/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)