Speed describes motion — Physical education, 11–13 years
Speed tells us how much distance an object covers in a certain time. It lets us compare a slow walk, a bicycle ride and a train using the same idea.
Distance shared by time
Speed is a way of saying how quickly something covers distance. A runner who travels 100 metres in 20 seconds has a speed of 5 metres per second. The direction is not included here: speed only tells how fast.
Why measure speed?
Distance alone does not tell a useful story: two cyclists may both travel 10 kilometres, but one may take twice as long. Speed was developed to compare journeys fairly, by joining distance with the time needed.
A cycling journey
A cyclist covers 12 kilometres in 40 minutes. First change 40 minutes to hours: 40 ÷ 60 = 2/3 hour. Then divide distance by time: 12 ÷ 2/3 = 18. The average speed is 18 kilometres per hour, even if the cyclist sometimes slowed down.
Mixing up the division
A common mistake is to calculate time ÷ distance instead of distance ÷ time. It feels reasonable because both numbers are being compared, but it gives a different quantity, not speed. Ask: how many distance units fit into one unit of time?
Speed outside school
Speed appears on a car’s dashboard, in train timetables and in sports results. It helps a sat-nav estimate arrival time and helps engineers set safe limits. A displayed speed is often an average or a momentary reading, so context matters.
Keep exploring
Other languages
Loading MyLeoNes™…