What is speed?
Speed tells us how fast something moves. A fast object covers more distance in the same time than a slow object. A racing car has a high speed, while a snail has a very low speed.
Key idea
Speed is how much distance an object moves in a certain time. Speed = distance divided by time.
Comparing speeds
If two runners start together, the faster runner reaches the finish line first. To find speed, we can measure the distance travelled and the time taken. We often measure speed in metres per second or kilometres per hour.
- More distance in the same time = faster
- Same distance in less time = faster
Example
A car travels 100 kilometres in 2 hours. Its speed is 100 divided by 2, which is 50 kilometres per hour.
Fast and slow in daily life
An aeroplane is much faster than a bicycle, and a bicycle is faster than walking. Speed helps us plan journeys, so we know how long a trip will take. It also helps drivers stay safe, because moving too fast on a busy road can be dangerous.