AQA · GCSE · Combined Science

    Course version: 8464 · Version from Sept 2018

    Acceleration: time, t, in seconds, s

    In acceleration calculations, time t is the duration over which the velocity changes, measured in seconds, s.

    Checked against the AQA 8464 specification (opens in a new tab) on .

    • Point 6 of 21
    • 3 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    In acceleration calculations, time t is the duration over which the velocity changes, measured in seconds, s. It is the interval between the initial and final velocity readings, not the total journey time unless the whole journey is the acceleration phase. For example, if a cyclist speeds up from 3 m/s to 11 m/s in 4 s, then t = 4 s and a = (11 m/s − 3 m/s) ÷ 4 s = 2 m/s². Time must be converted to seconds before substitution: 2 minutes becomes 120 s, and 0.5 minutes becomes 30 s. Using the correct time interval ensures the acceleration value is accurate and carries the unit m/s².

    What earns the marks

    • Identifies t as the time taken for the velocity change, measured in seconds, s.
    • Selects the correct time interval from the question rather than a total journey time.
    • Converts minutes or other units into seconds before substituting into a = ∆v ÷ t.
    • Substitutes t correctly into the acceleration equation and keeps the unit s.
    • Uses the time value consistently when rearranging to find ∆v or t.

    Common mistakes and how to put them right

    • Using minutes directly in the equation.

      Put it right by converting to seconds, for example 2 minutes = 120 s.

    • Choosing the total journey time instead of the time during which velocity changed.

      Put it right by identifying the start and end of the acceleration phase.

    • Confusing time t with speed or distance values.

      Put it right by checking that the value has the unit s before substitution.

    Exam tips

    • Write the time with its unit, for example t = 4 s, before substituting it.
    • If time is given in minutes, convert immediately and show the conversion line.
    • Check that the time interval matches the initial and final velocities you used.

    Try the lesson

    The start of the Acceleration: time, t, in seconds, s lesson, made from checked teaching notes for this specification point.

    Have a go first

    A cyclist speeds up from rest. A student records the time taken for this change in velocity as 0.4 minutes. What is this time in seconds?

    Listen

    In acceleration calculations, time t is the duration over which the velocity changes, measured in seconds, s. It is the interval between the initial and final velocity readings, not the total journey time unless the whole journey is the acceleration phase. For example, if a cyclist speeds up from 3 m/s to 11 m/s in 4 s, then t = 4 s and a = (11 m/s − 3 m/s) ÷ 4 s = 2 m/s². Time must be converted to seconds before substitution: 2 minutes becomes 120 s, and 0.5 minutes becomes 30 s. Using the correct time interval ensures the acceleration value is accurate and carries the unit m/s². A strong answer earns marks for these points. Identifies t as the time taken for the velocity change, measured in seconds, s. Selects the correct time interval from the question rather than a total journey time. Converts minutes or other units into seconds before substituting into a = ∆v ÷ t. Substitutes t correctly into the acceleration equation and keeps the unit s. A common slip: Using minutes directly in the equation. Instead, converting to seconds, for example 2 minutes = 120 s. Exam tip: Write the time with its unit, for example t = 4 s, before substituting it.

    See it

    A top-down flowchart. The first box says identify start and end of acceleration phase, which leads to a box saying select the time interval for the velocity change. This leads to a decision box asking is time given in minutes. The yes branch goes to a box saying convert to seconds, which then joins the no branch, which says time already in seconds, s. Both lead to a box saying write t with unit s, then to a box saying substitute t into a = ∆v ÷ t, and finally to a box saying acceleration in m/s².
    It shows the steps for choosing the correct time interval, converting it to seconds and substituting it into the acceleration equation.

    Key words

    Say what each word means before you turn the card.

    Time as a measured interval

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

    Unit conversion to seconds

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

    Selecting relevant data from a scenario

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

    See every definition
    Time as a measured interval
    The duration over which the velocity changes, being the interval between the initial and final velocity readings rather than the total journey time unless the whole journey is the acceleration phase.
    Unit conversion to seconds
    Changing a time given in minutes or other units into seconds before substitution, for example 2 minutes becomes 120 s and 0.5 minutes becomes 30 s.
    Selecting relevant data from a scenario
    Identifying the start and end of the acceleration phase so the correct time interval is chosen from the question rather than a total journey time.

    Label the diagram

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

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. The first box says identify start and end of acceleration phase, which leads to a box saying select the time interval for the velocity change. This leads to a decision box asking is time given in minutes. The yes branch goes to a box saying convert to seconds, which then joins the no branch, which says time already in seconds, s. Both lead to a box saying write t with unit s, then to a box saying substitute t into a = ∆v ÷ t, and finally to a box saying acceleration in m/s².

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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