--- title: Friction: the grip that stops and helps — a lesson of Mova's school · trees and pragmatics description: «Friction: the grip that stops and helps», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Friction is the grip between two surfaces that touch: rough surfaces pressed hard together grip a lot, smooth ones hardly at all. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/) [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/) / Friction: the grip that stops and helps # Friction: the grip that stops and helps Lesson 6 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/6-friction-the-grip/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/0/) — Friction is the grip between two surfaces that touch: rough surfaces pressed hard together grip a lot, smooth ones hardly at all. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/1/) — Slide in your socks on a polished floor and you glide; do it in trainers and the rubber grips and stops you at once. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/2/) — Friction slows things down, but it also lets you walk, stop and hold things, and the bumpy soles of your shoes are made to grip. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/3/) — Rub your hands together on a cold day and they warm up: friction always turns some movement into heat. - [4](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/4/) — Bike brakes use this too, squeezing rubber pads against the wheel until the speed turns into heat. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/5/) — Friction is the grip between two touching surfaces; rough surfaces and surfaces pressed hard together grip more. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/6/) — Ice has a thin slippery layer on top, so skates hardly grip, but scientists still argue about exactly why ice is so slippery. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/7/) — Shoe soles have bumps that grip the ground and grooves that push away water and mud, and football boots have studs that dig into grass. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/8/) — Rubbing your hands makes friction, and friction turns movement into heat; a rope rushing through your hands can even burn them. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/9/) — Bike brakes squeeze rubber pads against the wheel, and the harder you squeeze, the more they grip. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/10/) — Wet brakes grip less, so you must brake earlier in the rain. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/11/) — The speed a bike loses when it brakes turns into heat in the pads and rim, which is why they are hot after a long ride downhill. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/12/) — On long mountain roads car brakes can get so hot that they stop working well, so drivers use low gears. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/13/) — A layer of water between tyres and road makes a car skid; this is called aquaplaning, and tyre treads push the water away, so worn-smooth "bald" tyres are dangerous in the rain. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/14/) — Sand and grit on icy paths give shoes and tyres something rough to grip, and salt melts the ice because salty water freezes at a lower temperature. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/15/) — A slide is faster on a smooth mat or in smooth shorts than in rough jeans, because smooth material rubs less; bare, sweaty legs grip a metal slide, squeak and slow you down. - [17](https://md.mova.elamur.ai/free/en/corpora/school/physics/6-friction-the-grip/17/) — Heavier things press harder on the floor and so have more friction. - ← previous: [Pushes and pulls all around us](https://md.mova.elamur.ai/free/en/corpora/school/physics/5-pushes-and-pulls-all-around-us/) - next →: [Living with friction: oil, wheels and grip](https://md.mova.elamur.ai/free/en/corpora/school/physics/7-living-with-friction/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)