OCR · A-Level · Physics
Course version: H556 · Version from Sept 2015
(b) graphical representations of displacement, speed, velocity and…
Full specification wording
Kinematics: (b) graphical representations of displacement, speed, velocity and acceleration
Motion graphs show how displacement, speed, velocity or acceleration vary with time.
Checked against the OCR H556 specification (opens in a new tab) on .
- Point 2 of 4
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Motion graphs show how displacement, speed, velocity or acceleration vary with time. On a displacement–time graph, the gradient gives velocity, so a horizontal line means rest and a straight sloping line means constant velocity. On a velocity–time graph, the gradient gives acceleration and the area between the line and the time axis gives displacement. Speed–time graphs give distance from area but lose direction. Acceleration–time graphs show how acceleration changes; the area under them gives velocity change. Always read the axis labels and units first, because the same shape means different things on different graphs.
What earns the marks
- Displacement–time gradient gives velocity.
- Velocity–time gradient gives acceleration.
- Area under a velocity–time graph gives displacement.
- Area under an acceleration–time graph gives velocity change.
- Speed–time graphs give distance from area but do not show direction.
Common mistakes and how to put them right
Reading area under a displacement–time graph as displacement.
Put it right: Area is not used on that graph; gradient gives velocity.
Using a speed–time graph to find displacement.
Put it right: It gives distance, because direction is lost.
Ignoring negative regions: area below the time axis counts as negative displacement for velocity–time graphs.
Exam tips
- Label axes and units before interpreting any gradient or area.
- Use tangent gradients for curved graphs and count squares for irregular areas.
- State whether an area represents displacement or distance according to the graph type.
Try the lesson
The start of the Kinematics: (b) graphical representations of displacement, speed, velocity and acceleration lesson, made from checked teaching notes for this specification point.
Listen
Motion graphs show how displacement, speed, velocity or acceleration vary with time. On a displacement–time graph, the gradient gives velocity, so a horizontal line means rest and a straight sloping line means constant velocity. On a velocity–time graph, the gradient gives acceleration and the area between the line and the time axis gives displacement. Speed–time graphs give distance from area but lose direction. Acceleration–time graphs show how acceleration changes; the area under them gives velocity change. Always read the axis labels and units first, because the same shape means different things on different graphs. A strong answer earns marks for these points. Displacement–time gradient gives velocity. Velocity–time gradient gives acceleration. Area under a velocity–time graph gives displacement. Area under an acceleration–time graph gives velocity change. Exam tip: Label axes and units before interpreting any gradient or area.
See it
Key words
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Graph gradients
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Area under graphs
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Motion representation
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Sign and direction
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See every definition
- Graph gradients
- On a displacement–time graph the gradient gives velocity, and on a velocity–time graph the gradient gives acceleration.
- Area under graphs
- The area between the line and the time axis gives displacement on a velocity–time graph and velocity change on an acceleration–time graph.
- Motion representation
- Graphs show how displacement, speed, velocity or acceleration vary with time, so axis labels and units must be read first.
- Sign and direction
- Area below the time axis counts as negative displacement for velocity–time graphs, and speed–time graphs give distance because direction is lost.
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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