Lesson 2 of 4
Calculating speed
Goal: Calculate speed from distance and time.
To find a speed, measure a distance and the time taken. Then divide.
speed = distance ÷ time
- Measure the distance with a tape measure or a metre rule. Measure the time with a stopwatch.
- The unit follows the measurements. Metres and seconds give m/s. Kilometres and hours give km/h.
- Most journeys have faster and slower parts. Total distance ÷ total time gives the average speed for the whole journey.
Worked example. A swimmer covers 50 m in 25 s. Speed = 50 m ÷ 25 s = 2 m/s.
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Key words in this lesson
Speed How far something travels in a certain time
Distance How far something has moved
Time How long something takes
Average speed Total distance divided by total time
Stopwatch An instrument that measures a time
Tape measure An instrument that measures a distance