Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
Recall and use the equations: a (average) speed (metre per second, m/s) =…
Full specification wording
Topic 2 – Motion and forces: 2.6 Recall and use the equations: a (average) speed (metre per second, m/s) = distance (metre, m) ÷ time (s) b distance travelled (metre, m) = average speed (metre per second, m/s) × time (s)
Average speed is the total distance travelled divided by the total time taken, measured in metres per second when distance is in metres and time in seconds.
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 6 of 32
Study notes
From the checked teaching notes for this specification point.
The idea
Average speed is the total distance travelled divided by the total time taken, measured in metres per second when distance is in metres and time in seconds. Rearranging gives distance travelled = average speed × time. Use the first form when you know distance and time and want speed; use the second when you know speed and time and want distance. Keep units consistent: convert 3 km to 3000 m and 2 minutes to 120 s before dividing, so 3000 m ÷ 120 s = 25 m/s. For a journey in stages, add the stage distances and the stage times to find the overall average speed rather than averaging the separate speeds. Check each answer by substituting it back into the other equation.
What earns the marks
- Selects average speed = distance ÷ time when distance and time are known.
- Selects distance travelled = average speed × time when speed and time are known.
- Converts distances to metres and times to seconds before substituting.
- Calculates an overall average speed from total distance and total time for a multi-stage journey.
Common mistakes and how to put them right
Divides time by distance instead of distance by time.
Put it right: Divide distance by time to obtain average speed.
Mixes units such as kilometres with seconds.
Put it right: Convert all quantities to metres and seconds first.
Averages the separate speeds of a two-stage journey.
Put it right: Divide total distance by total time instead.
Exam tips
- Write down the equation, then substitute values with units before calculating to avoid unit slips.
- Convert minutes to seconds by multiplying by 60 and kilometres to metres by multiplying by 1000.
- Check a distance answer by dividing it by the time to recover the average speed.
Try the lesson
The start of the Topic 2 – Motion and forces: 2.6 Recall and use the equations: a (average) speed (metre per second, m/s) = distance (metre, m) ÷ time (s) b distance travelled (metre, m) = average speed (metre per second, m/s) × time (s) lesson, made from checked teaching notes for this specification point.
Have a go first
A runner covers 200 m in 25 s. What is the runner's average speed?
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Test your understanding of Topic 2 – Motion and forces: 2.6 Recall and use the equations: a (average) speed (metre per second, m/s) = distance (metre, m) ÷ time (s) b distance travelled (metre, m) = average speed (metre per second, m/s) × time (s)
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