AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Students should be able to express a displacement in terms of both the…
Full specification wording
Distance and displacement: Students should be able to express a displacement in terms of both the magnitude and direction.
Expressing a displacement means giving two pieces of information: how far the finish point is from the start point in a straight line, and the direction of that line.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 3 of 3
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Expressing a displacement means giving two pieces of information: how far the finish point is from the start point in a straight line, and the direction of that line. The magnitude is a length, such as 5 m, and the direction may be given as a compass direction, a bearing, or an angle from a stated line. For example, a displacement of 5 m on a bearing of 053° tells you both the straight-line distance and the direction. To produce this, draw the journey as a vector diagram, join start to finish with a straight line, measure its length using the scale, and measure its angle from a reference direction such as north. A displacement written without direction is incomplete because it does not tell you where the finish point lies.
What earns the marks
- States a numerical magnitude with a unit for the straight-line distance from start to finish.
- States a direction using a compass point, a bearing, or an angle from a named reference line.
- Uses a scale diagram to measure the straight-line length and the angle of the displacement.
- Converts a measured angle into a three-figure bearing when the question requires a bearing.
- Checks that the magnitude and direction refer to the same straight line from start point to finish point.
- Recognises that changing either the magnitude or the direction changes the displacement.
Common mistakes and how to put them right
Writing only a magnitude, such as '5 m'.
Put it right by adding the direction, for example '5 m north'.
Writing only a direction, such as 'north'.
Put it right by adding the straight-line distance with its unit.
Measuring the angle from the wrong reference line.
Put it right by marking north or the stated reference clearly before measuring.
Exam tips
- Choose a sensible scale for a vector diagram and write it down so the marker can follow your measurement.
- Give bearings as three-figure angles, for example 053° rather than 53°.
- Include the unit with the magnitude and name the reference direction used for the angle.
Try the lesson
The start of the Distance and displacement: Students should be able to express a displacement in terms of both the magnitude and direction. lesson, made from checked teaching notes for this specification point.
Have a go first
A walker moves 7 m due north from a bench. Which statement gives the displacement of the walker from the bench?
Listen
Expressing a displacement means giving two pieces of information: how far the finish point is from the start point in a straight line, and the direction of that line. The magnitude is a length, such as 5 m, and the direction may be given as a compass direction, a bearing, or an angle from a stated line. For example, a displacement of 5 m on a bearing of 053° tells you both the straight-line distance and the direction. To produce this, draw the journey as a vector diagram, join start to finish with a straight line, measure its length using the scale, and measure its angle from a reference direction such as north. A displacement written without direction is incomplete because it does not tell you where the finish point lies. A strong answer earns marks for these points. States a numerical magnitude with a unit for the straight-line distance from start to finish. States a direction using a compass point, a bearing, or an angle from a named reference line. Uses a scale diagram to measure the straight-line length and the angle of the displacement. Converts a measured angle into a three-figure bearing when the question requires a bearing. A common slip: Writing only a magnitude, such as '5 m'. Instead, adding the direction, for example '5 m north'. Exam tip: Choose a sensible scale for a vector diagram and write it down so the marker can follow your measurement.
Key words
Say what each word means before you turn the card.
Magnitude
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Direction
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Scale diagram
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Three-figure bearing
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See every definition
- Magnitude
- A length, such as 5 m, giving how far the finish point is from the start point in a straight line.
- Direction
- May be given as a compass direction, a bearing, or an angle from a stated line.
- Scale diagram
- A vector diagram of the journey in which the straight-line length and the angle of the displacement are measured.
- Three-figure bearing
- A measured angle converted into this form when the question requires a bearing, for example 053° rather than 53°.
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