AQA · GCSE · Physics

    Course version: 8463 · Version from Sept 2016

    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: distance travelled = speed × time s = v t distance, s, in metres, m speed, v, in metres per second, m/s time, t, in seconds, s Students should be able to calculate average speed for non-uniform motion.

    This equation gives the distance covered when the speed is steady, with distance in metres, speed in metres per second and time in seconds.

    Checked against the AQA 8463 specification (opens in a new tab) on .

    • Point 9 of 9
    • 3 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    This equation gives the distance covered when the speed is steady, with distance in metres, speed in metres per second and time in seconds. Rearranged, the speed is distance divided by time and the time is distance divided by speed, and any correct rearrangement is credited. Where the motion is not steady, apply the equation stage by stage and add the distances: a car at 7.5 m/s for 3.0 s covers 22.5 m, then at 15 m/s for 2.0 s covers a further 30 m, giving 52.5 m in total. The average speed for the whole journey is then the total distance divided by the total time, which here is 10.5 m/s and is not the average of the two speeds. Convert minutes and hours into seconds before substituting.

    What earns the marks

    • The equation distance = speed × time, or any correct rearrangement.
    • Calculating the distance for each stage of a journey separately.
    • Adding the stage distances to give the total distance.
    • An average speed found from the total distance divided by the total time.

    Common mistakes and how to put them right

    • Averaging the two speeds instead of dividing the total distance by the total time.

    • Applying the equation across a stage in which the speed changes.

    • Leaving a time in minutes while the speed is in metres per second.

    • Rearranging the equation so that time becomes speed divided by distance.

    Exam tips

    • Split a journey at every change of speed and tabulate each stage before calculating.
    • The average of two speeds is only correct when the two stages take equal times.

    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: distance travelled = speed × time s = v t distance, s, in metres, m speed, v, in metres per second, m/s time, t, in seconds, s Students should be able to calculate average speed for non-uniform motion. 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 s = v t, what distance does the cyclist travel?

    Listen

    This equation gives the distance covered when the speed is steady, with distance in metres, speed in metres per second and time in seconds. Rearranged, the speed is distance divided by time and the time is distance divided by speed, and any correct rearrangement is credited. Where the motion is not steady, apply the equation stage by stage and add the distances: a car at 7.5 m/s for 3.0 s covers 22.5 m, then at 15 m/s for 2.0 s covers a further 30 m, giving 52.5 m in total. The average speed for the whole journey is then the total distance divided by the total time, which here is 10.5 m/s and is not the average of the two speeds. Convert minutes and hours into seconds before substituting. A strong answer earns marks for these points. the equation distance = speed × time, or any correct rearrangement. calculating the distance for each stage of a journey separately. adding the stage distances to give the total distance. an average speed found from the total distance divided by the total time. Exam tip: Split a journey at every change of speed and tabulate each stage before calculating.

    See it

    A flowchart running top to bottom. The first box says 'Split journey at every change of speed'. From it, two arrows lead to two boxes side by side: 'Stage 1: distance = speed × time' and 'Stage 2: distance = speed × time'. Arrows from both of these lead to a box saying 'Add stage distances to give total distance'. An arrow from that box leads to a final box saying 'Average speed = total distance ÷ total time'.
    Shows how a journey with two constant-speed stages is split, each stage distance calculated, added to give the total distance, and used to find the average speed.

    Key words

    Say what each word means before you turn the card.

    distance equation

    Try answering aloud or in your head before turning the card.

    constant speed

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    staged journeys

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    See every definition
    distance equation
    Distance travelled equals speed multiplied by time, with distance in metres, speed in metres per second and time in seconds.
    constant speed
    The speed is steady, so the distance travelled in a specific time can be calculated using the equation.
    staged journeys
    Where the motion is not steady, apply the equation stage by stage and add the distances.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 2 boxes numbered instead of named. A flowchart running top to bottom. The first box says 'Split journey at every change of speed'. From it, two arrows lead to two boxes side by side: 'Stage 1: distance = speed × time' and 'Stage 2: distance = speed × time'. Arrows from both of these lead to a box saying 'Add stage distances to give total distance'. An arrow from that box leads to a final box saying 'Average speed = total distance ÷ total time'.

    • 1Box 1

    • 2Box 2

    0 of 2 labelled

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    Test your understanding of Speed: For an object moving at constant speed the distance travelled in a specific time can be calculated using the equation: distance travelled = speed × time s = v t distance, s, in metres, m speed, v, in metres per second, m/s time, t, in seconds, s Students should be able to calculate average speed for non-uniform motion.

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