AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Speed: Speed does not involve direction. Speed is a scalar quantity.
Speed measures how quickly distance is covered, but it says nothing about the direction of travel.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 1 of 18
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Speed measures how quickly distance is covered, but it says nothing about the direction of travel. Because it has magnitude only, speed is a scalar quantity. For example, a cyclist moving at 6 m/s has that speed whether heading north, south or around a bend; the direction is simply not part of the value. This distinguishes speed from velocity, which is a vector and includes direction. When you calculate speed using speed = distance ÷ time, the answer is a scalar with units such as m/s, and no direction needs to be stated. Two objects can have identical speeds while moving in completely different directions, and both values remain correct because direction is excluded. Recognising scalar quantities helps you choose the right quantity when describing motion and avoids adding unnecessary directional information.
What earns the marks
- States that speed has magnitude only and no direction is involved.
- Defines a scalar quantity as one having magnitude but no direction.
- Classifies speed as a scalar quantity.
- Distinguishes speed from velocity, which is a vector because it includes direction.
- Uses speed = distance ÷ time and gives the answer with a unit such as m/s without a direction.
Common mistakes and how to put them right
Writing that speed is a vector because it describes motion.
Put it right by stating that speed has magnitude only, while velocity includes direction.
Adding a direction such as 'north' to a speed value.
Put it right by removing the direction, because speed is scalar.
Confusing speed with velocity when the direction changes.
Put it right by noting that a change of direction changes velocity but not necessarily speed.
Exam tips
- When asked to classify a quantity, state both the magnitude-only property and the scalar label.
- If a question gives a direction, check whether it asks for speed or velocity before answering.
- In calculations, give the unit with the numerical answer and do not attach a direction to a speed.
Try the lesson
The start of the Speed: Speed does not involve direction. Speed is a scalar quantity. lesson, made from checked teaching notes for this specification point.
Have a go first
A cyclist travels 60 metres in 10 seconds. Which quantity describes the cyclist's motion as 6 m/s without any direction?
Listen
Speed measures how quickly distance is covered, but it says nothing about the direction of travel. Because it has magnitude only, speed is a scalar quantity. For example, a cyclist moving at 6 m/s has that speed whether heading north, south or around a bend; the direction is simply not part of the value. This distinguishes speed from velocity, which is a vector and includes direction. When you calculate speed using speed = distance ÷ time, the answer is a scalar with units such as m/s, and no direction needs to be stated. Two objects can have identical speeds while moving in completely different directions, and both values remain correct because direction is excluded. Recognising scalar quantities helps you choose the right quantity when describing motion and avoids adding unnecessary directional information. A strong answer earns marks for these points. States that speed has magnitude only and no direction is involved. Defines a scalar quantity as one having magnitude but no direction. Classifies speed as a scalar quantity. Distinguishes speed from velocity, which is a vector because it includes direction. A common slip: Writing that speed is a vector because it describes motion. Instead, stating that speed has magnitude only, while velocity includes direction. Exam tip: When asked to classify a quantity, state both the magnitude-only property and the scalar label.
Key words
Say what each word means before you turn the card.
Speed
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Scalar quantity
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Velocity
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Speed = distance ÷ time
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See every definition
- Speed
- Measures how quickly distance is covered, but says nothing about the direction of travel.
- Scalar quantity
- One having magnitude but no direction.
- Velocity
- A vector that includes direction, which distinguishes it from speed.
- Speed = distance ÷ time
- The calculation whose answer is a scalar with units such as m/s, and no direction needs to be stated.
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