AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
For an object moving at constant speed the distance travelled in a…
Full specification wording
Speed: For an object moving at constant speed the distance travelled in a specific time can be calculated using the equation:
When an object moves at constant speed, it covers the same distance every second, so distance, speed and time are linked by a simple relationship.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 12 of 18
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
When an object moves at constant speed, it covers the same distance every second, so distance, speed and time are linked by a simple relationship. The equation is distance travelled = speed × time, often written s = v × t. If speed is in metres per second and time is in seconds, distance comes out in metres. For example, a cyclist moving at a constant 6 m/s for 20 s travels 6 m/s × 20 s = 120 m. Rearranged, speed = distance ÷ time and time = distance ÷ speed. Constant speed means the value does not change during the motion, so the same speed can be used throughout the calculation. Always convert units first: 3 minutes becomes 180 s, and 36 km/h becomes 10 m/s, before substituting into the equation.
What earns the marks
- States or selects the equation distance travelled = speed × time for constant-speed motion.
- Rearranges the equation correctly when asked for speed or time rather than distance.
- Converts time to seconds and speed to metres per second before substituting.
- Substitutes values with units into the equation and evaluates the answer accurately.
- Gives the final answer with the correct unit, such as metres, and a sensible size.
- Recognises that the equation applies when speed is constant, and that changing speed needs a different approach.
Common mistakes and how to put them right
Mixing units, such as using minutes with a speed in m/s.
Put it right: Convert 3 minutes to 180 s first.
Rearranging incorrectly, for example dividing when the question asks for time.
Put it right: Time = distance ÷ speed, not distance × speed.
Assuming the equation works for accelerating objects.
Put it right: It applies to constant speed only, so a changing speed needs average speed or a different method.
Exam tips
- Write the equation, rearrange it before substituting numbers, then substitute and evaluate.
- Include units at every stage and check that the final unit matches the quantity asked for.
- For a two-step question, convert units first, then calculate, so the arithmetic stays clear.
Try the lesson
The start of the Speed: For an object moving at constant speed the distance travelled in a specific time can be calculated using the equation: lesson, made from checked teaching notes for this specification point.
Have a go first
A cyclist travels at a constant speed of 6 m/s for 20 s. Using distance = speed × time, what distance does the cyclist travel?
Listen
When an object moves at constant speed, it covers the same distance every second, so distance, speed and time are linked by a simple relationship. The equation is distance travelled = speed × time, often written s = v × t. If speed is in metres per second and time is in seconds, distance comes out in metres. For example, a cyclist moving at a constant 6 m/s for 20 s travels 6 m/s × 20 s = 120 m. Rearranged, speed = distance ÷ time and time = distance ÷ speed. Constant speed means the value does not change during the motion, so the same speed can be used throughout the calculation. Always convert units first: 3 minutes becomes 180 s, and 36 km/h becomes 10 m/s, before substituting into the equation. A strong answer earns marks for these points. States or selects the equation distance travelled = speed × time for constant-speed motion. Rearranges the equation correctly when asked for speed or time rather than distance. Converts time to seconds and speed to metres per second before substituting. Substitutes values with units into the equation and evaluates the answer accurately. Exam tip: Write the equation, rearrange it before substituting numbers, then substitute and evaluate.
See it
Key words
Say what each word means before you turn the card.
Constant speed
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Distance, speed and time relationship
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Rearranging equations
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Unit conversion and standard units
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See every definition
- Constant speed
- The value does not change during the motion, so the same speed can be used throughout the calculation.
- Distance, speed and time relationship
- Distance travelled = speed × time, linking the distance covered to the speed and the time taken.
- Rearranging equations
- The equation can be rearranged so that speed = distance ÷ time and time = distance ÷ speed.
- Unit conversion and standard units
- Units are converted first, such as minutes to seconds and km/h to m/s, before substituting into the equation.
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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