AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Displacement includes both the distance an object moves, measured in a…
Full specification wording
Distance and displacement: Displacement includes both the distance an object moves, measured in a straight line from the start point to the finish point and the direction of that straight line. Displacement is a vector quantity.
Displacement is the straight-line separation of an object's finish point from its start point, together with the direction of that line.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 2 of 3
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Displacement is the straight-line separation of an object's finish point from its start point, together with the direction of that line. It is not the total path length travelled. For example, a runner who completes one 400 m lap on a track finishes at the start point, so the displacement is 0 m even though the distance travelled is 400 m. If a walker moves 3 m east then 4 m north, the distance travelled is 7 m, but the displacement is 5 m in a direction between east and north, found by drawing the two legs tip-to-tail and measuring the closing straight line. Because displacement has both magnitude and direction, it is a vector quantity; distance has magnitude only and is a scalar. Displacement can be positive or negative along a chosen line, and zero when start and finish coincide.
What earns the marks
- Defines displacement as the straight-line distance from start point to finish point, not the total path length.
- States that displacement includes the direction of the straight line from start to finish.
- Classifies displacement as a vector quantity because it has both magnitude and direction.
- Distinguishes displacement from distance, which is a scalar and measures the whole path travelled.
- Applies the idea to a closed path, such as one full lap, where displacement is zero but distance is not.
- Uses a scale drawing or vector triangle to find the magnitude and direction of a resultant displacement.
Common mistakes and how to put them right
Treating displacement as the total distance travelled.
Put it right by identifying the straight line from start to finish and ignoring the route taken.
Giving only a number for displacement.
Put it right by adding a direction, such as '5 m north-east' or '5 m on a bearing of 053°'.
Assuming displacement must be positive.
Put it right by allowing negative values when the finish point lies in the opposite direction along a chosen axis.
Exam tips
- Underline the words 'straight line' and 'direction' in the question so both parts of the displacement definition are addressed.
- When a journey has two legs, sketch them tip-to-tail and draw the closing straight line before calculating anything.
- Check whether the question asks for distance or displacement; a full lap or a return journey often has zero displacement.
Try the lesson
The start of the Distance and displacement: Displacement includes both the distance an object moves, measured in a straight line from the start point to the finish point and the direction of that straight line. Displacement is a vector quantity. lesson, made from checked teaching notes for this specification point.
Have a go first
A pupil walks 30 m north from a bench to a tree. What is the displacement of the pupil from the bench?
Listen
Displacement is the straight-line separation of an object's finish point from its start point, together with the direction of that line. It is not the total path length travelled. For example, a runner who completes one 400 m lap on a track finishes at the start point, so the displacement is 0 m even though the distance travelled is 400 m. If a walker moves 3 m east then 4 m north, the distance travelled is 7 m, but the displacement is 5 m in a direction between east and north, found by drawing the two legs tip-to-tail and measuring the closing straight line. Because displacement has both magnitude and direction, it is a vector quantity; distance has magnitude only and is a scalar. Displacement can be positive or negative along a chosen line, and zero when start and finish coincide. A strong answer earns marks for these points. Defines displacement as the straight-line distance from start point to finish point, not the total path length. States that displacement includes the direction of the straight line from start to finish. Classifies displacement as a vector quantity because it has both magnitude and direction. Distinguishes displacement from distance, which is a scalar and measures the whole path travelled. A common slip: Treating displacement as the total distance travelled. Instead, identifying the straight line from start to finish and ignoring the route taken. Exam tip: Underline the words 'straight line' and 'direction' in the question so both parts of the displacement definition are addressed.
See it
Key words
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Displacement
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Vector quantity
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Scalar
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Distance
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See every definition
- Displacement
- The distance an object moves, measured in a straight line from the start point to the finish point, together with the direction of that straight line.
- Vector quantity
- A quantity that has both magnitude and direction, which is why displacement is one.
- Scalar
- A quantity that has magnitude only, as distance does.
- Distance
- The whole path travelled, which has magnitude only and is not the straight-line separation from start to finish.
Label the diagram
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1Box 1
2Box 2
3Box 3
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