AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Speed: distance travelled = speed × time
This relationship links the distance an object travels to how fast it moves and how long it moves for.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 13 of 18
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
This relationship links the distance an object travels to how fast it moves and how long it moves for. Speed is the rate of change of distance: a car travelling at 15 m/s for 8 s covers 15 × 8 = 120 m. Rearranged, speed = distance ÷ time and time = distance ÷ speed. The equation applies to motion along any path; if speed changes, it gives an average speed. Units must be consistent: distance in metres, time in seconds, speed in metres per second (m/s). Convert first, for example 3 minutes = 180 s, then substitute. In calculations, write the equation, substitute values with units, and state the unit in the answer.
What earns the marks
- State the equation distance travelled = speed × time and identify the three quantities involved.
- Substitute values correctly into the equation, keeping units consistent (m, s, m/s).
- Rearrange the equation to find speed (speed = distance ÷ time) or time (time = distance ÷ speed) when required.
- Convert non-SI units before calculating, for example minutes to seconds or kilometres to metres.
- Give the answer with the correct unit and a sensible number of significant figures.
- Interpret the result in context, such as stating the distance covered or the average speed over a journey.
Common mistakes and how to put them right
Multiplying speed by time but forgetting to convert minutes to seconds.
Put it right by converting all times to seconds before substituting.
Dividing distance by speed when asked for distance.
Put it right by rearranging the equation first and checking which quantity is unknown.
Writing the unit as m/s for a distance.
Put it right by matching the unit to the quantity: distance in m, speed in m/s, time in s.
Exam tips
- Always write the equation before substituting numbers so the examiner can see your method.
- Include units in every step and in the final answer; a numerical answer without a unit may lose credit.
- Check that your answer is reasonable: a car at 20 m/s for 10 s should travel about 200 m, not 2 m or 2000 m.
Try the lesson
The start of the Speed: distance travelled = speed × time lesson, made from checked teaching notes for this specification point.
Have a go first
A cyclist travels at a steady speed of 6 m/s for 20 s. How far does the cyclist travel?
Listen
This relationship links the distance an object travels to how fast it moves and how long it moves for. Speed is the rate of change of distance: a car travelling at 15 m/s for 8 s covers 15 × 8 = 120 m. Rearranged, speed = distance ÷ time and time = distance ÷ speed. The equation applies to motion along any path; if speed changes, it gives an average speed. Units must be consistent: distance in metres, time in seconds, speed in metres per second (m/s). Convert first, for example 3 minutes = 180 s, then substitute. In calculations, write the equation, substitute values with units, and state the unit in the answer. A strong answer earns marks for these points. State the equation distance travelled = speed × time and identify the three quantities involved. Substitute values correctly into the equation, keeping units consistent (m, s, m/s). Rearrange the equation to find speed (speed = distance ÷ time) or time (time = distance ÷ speed) when required. Convert non-SI units before calculating, for example minutes to seconds or kilometres to metres. A common slip: Multiplying speed by time but forgetting to convert minutes to seconds. Instead, converting all times to seconds before substituting. Exam tip: Always write the equation before substituting numbers so the examiner can see your method.
See it
Key words
Say what each word means before you turn the card.
Rate of change
Try answering aloud or in your head before turning the card.
Equation rearrangement
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SI units and conversion
Try answering aloud or in your head before turning the card.
Average speed in context
Try answering aloud or in your head before turning the card.
See every definition
- Rate of change
- Speed is the rate of change of distance, linking how far an object travels to how long it moves for.
- Equation rearrangement
- The relationship can be rearranged to give speed = distance ÷ time and time = distance ÷ speed.
- SI units and conversion
- Units must be consistent, with distance in metres, time in seconds and speed in metres per second, converting first before substituting.
- Average speed in context
- If speed changes, the equation gives an average speed, and the result can be interpreted as the distance covered or the average speed over a journey.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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