OCR · GCSE · Physics

    Course version: J249 · Version from Sept 2018

    Relate changes and differences in motion to appropriate distance-time, and…

    Full specification wording

    Motion: relate changes and differences in motion to appropriate distance-time, and velocity-time graphs; interpret lines and slopes

    Choose the graph that matches the motion described.

    Checked against the OCR J249 specification (opens in a new tab) on .

    • Point 9 of 14
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Choose the graph that matches the motion described. On a distance-time graph the slope gives speed: a horizontal line means the object is stationary, a straight sloping line means constant speed, and a steeper line means greater speed. On a velocity-time graph the slope gives acceleration: a horizontal line means constant velocity, a rising line means acceleration and a falling line means deceleration, while the area under the line gives the distance travelled. A curved line on either graph shows changing speed or changing acceleration. In multiple-choice questions, match each feature of the described motion, such as rest, steady speed, speeding up or slowing down, to the correct line shape and slope on the right type of graph.

    What earns the marks

    • Matches a horizontal line on a distance-time graph to a stationary object.
    • Matches the slope of a distance-time graph to speed, with a steeper slope showing greater speed.
    • Matches the slope of a velocity-time graph to acceleration, including deceleration for a downward slope.
    • Matches a horizontal line on a velocity-time graph to motion at constant velocity.
    • Relates the area under a velocity-time graph to the distance travelled.
    • Recognises a curved line as showing changing speed or changing acceleration.

    Common mistakes and how to put them right

    • Reads the slope of a distance-time graph as acceleration.

      Put it right by stating that the slope of a distance-time graph gives speed.

    • Reads the slope of a velocity-time graph as speed.

      Put it right by stating that the slope of a velocity-time graph gives acceleration.

    • Treats a horizontal line on a velocity-time graph as a stationary object.

      Put it right by stating that it shows constant velocity.

    • Uses the line height on a distance-time graph as the distance travelled per second.

      Put it right by using the slope to find speed.

    Exam tips

    • Identify the graph type first, because the same line shape means different things on distance-time and velocity-time graphs.
    • Check the axis labels and units before interpreting a slope.
    • Sketch the described motion quickly, then compare your sketch with each option.

    Try the lesson

    The start of the Motion: relate changes and differences in motion to appropriate distance-time, and velocity-time graphs; interpret lines and slopes lesson, made from checked teaching notes for this specification point.

    Have a go first

    On a distance-time graph, a straight horizontal line shows an object that is doing what?

    Listen

    Choose the graph that matches the motion described. On a distance-time graph the slope gives speed: a horizontal line means the object is stationary, a straight sloping line means constant speed, and a steeper line means greater speed. On a velocity-time graph the slope gives acceleration: a horizontal line means constant velocity, a rising line means acceleration and a falling line means deceleration, while the area under the line gives the distance travelled. A curved line on either graph shows changing speed or changing acceleration. In multiple-choice questions, match each feature of the described motion, such as rest, steady speed, speeding up or slowing down, to the correct line shape and slope on the right type of graph. A strong answer earns marks for these points. Matches a horizontal line on a distance-time graph to a stationary object. Matches the slope of a distance-time graph to speed, with a steeper slope showing greater speed. Matches the slope of a velocity-time graph to acceleration, including deceleration for a downward slope. Matches a horizontal line on a velocity-time graph to motion at constant velocity. A common slip: Reads the slope of a distance-time graph as acceleration. Instead, stating that the slope of a distance-time graph gives speed. Exam tip: Identify the graph type first, because the same line shape means different things on distance-time and velocity-time graphs.

    See it

    A top-down flowchart. The first box says identify the graph type, leading to a decision box asking distance-time or velocity-time. The distance-time branch leads to a box saying slope gives speed, which branches into three boxes: horizontal line means stationary, straight sloping line means constant speed, and steeper line means greater speed. The velocity-time branch leads to a box saying slope gives acceleration, which branches into three boxes: horizontal line means constant velocity, rising line means acceleration, and falling line means deceleration. A separate box under the velocity-time branch says area under line gives distance travelled.
    It shows how to identify the graph type first, then read the slope of a distance-time graph as speed and the slope of a velocity-time graph as acceleration, with the area under a velocity-time graph giving distance travelled.

    Key words

    Say what each word means before you turn the card.

    distance-time graph

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

    velocity-time graph

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

    slope

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

    curved line

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

    See every definition
    distance-time graph
    A graph on which the slope gives speed: a horizontal line means the object is stationary, a straight sloping line means constant speed, and a steeper line means greater speed.
    velocity-time graph
    A graph on which the slope gives acceleration: a horizontal line means constant velocity, a rising line means acceleration and a falling line means deceleration, while the area under the line gives the distance travelled.
    slope
    The feature of a line that gives speed on a distance-time graph and acceleration on a velocity-time graph.
    curved line
    A line on either graph that shows changing speed or changing acceleration.

    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 the graph type, leading to a decision box asking distance-time or velocity-time. The distance-time branch leads to a box saying slope gives speed, which branches into three boxes: horizontal line means stationary, straight sloping line means constant speed, and steeper line means greater speed. The velocity-time branch leads to a box saying slope gives acceleration, which branches into three boxes: horizontal line means constant velocity, rising line means acceleration, and falling line means deceleration. A separate box under the velocity-time branch says area under line gives distance travelled.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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