--- title: Speed: fast and slow — a lesson of Mova's school · trees and pragmatics description: «Speed: fast and slow», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Speed is how far you go in a certain time: when the car's speedometer shows 50, the car would cover 50 kilometres if it kept that speed for a whole h --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/) [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/) / Speed: fast and slow # Speed: fast and slow Lesson 36 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/36-speed-fast-and-slow/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/0/) — Speed is how far you go in a certain time: when the car's speedometer shows 50, the car would cover 50 kilometres if it kept that speed for a whole hour. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/1/) — Moving things keep moving the way they are moving until something stops or turns them; this is called inertia, and it is why you lurch forward when the car brakes. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/2/) — On a smooth train a ball you drop lands at your feet, because the ball was already moving along with the train and you. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/3/) — To speed up, slow down or turn, you need a push: the engine pushes the car faster, the brakes slow it, and the ground pushes sideways on your feet when you turn. - [4](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/4/) — A fast car carries much more energy than a slow one, so it needs a much longer way to stop, and that is why the speed limit outside a school is low. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/5/) — Speed is how far something goes in a certain time; 50 kilometres an hour means 50 kilometres in one hour at that speed. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/6/) — To compare speeds you need both the distance and the time; the winner of a race covers the distance in the least time. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/7/) — A cheetah can sprint at about 100 kilometres an hour for a short time, while a snail takes a few minutes to go a metre. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/8/) — Moving things keep moving the way they are going until something stops or turns them; this is inertia. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/9/) — A ball dropped on a smooth train lands at your feet because it was already moving with the train. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/10/) — When a car brakes, your body keeps moving forward; when it turns sharply, you lurch outwards. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/11/) — A quick pull on a tablecloth can leave the dishes behind because they are slow to start moving, but a slow pull drags them with it. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/12/) — A lighter car speeds up faster than a heavy lorry with the same engine. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/13/) — At twice the speed, a car needs about four times the braking distance. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/14/) — Before braking even starts, a driver needs a moment to see, think and press the pedal, and the car carries on at full speed meanwhile; a phone makes that moment longer. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/15/) — A passenger plane flies at about 900 kilometres an hour, many times faster than a car, yet high in the sky it is so far away that it seems to crawl. - [16](https://md.mova.elamur.ai/free/en/corpora/school/physics/36-speed-fast-and-slow/16/) — To turn, you need a sideways push from the ground on your feet, which is why footballers slip turning on wet grass. - ← previous: [Pulleys, gears and big machines](https://md.mova.elamur.ai/free/en/corpora/school/physics/35-pulleys-gears-and-big-machines/) - next →: [Seat belts, crashes and keeping safe](https://md.mova.elamur.ai/free/en/corpora/school/physics/37-seat-belts-crashes-and-keeping-safe/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)