AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
The velocity of an object is its speed in a given direction. Velocity is a…
Full specification wording
Velocity: The velocity of an object is its speed in a given direction. Velocity is a vector quantity.
Velocity describes how fast an object moves and the direction in which it moves.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 1 of 3
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Velocity describes how fast an object moves and the direction in which it moves. Speed alone gives only the magnitude, for example 8 m/s, whereas velocity adds a direction, for example 8 m/s due north. Because direction is part of the definition, velocity is a vector quantity: a change in direction changes velocity even if the speed stays constant. For example, a car going round a roundabout at a steady 10 m/s has changing velocity because its direction keeps changing. In calculations, a negative velocity indicates motion in the opposite direction to a chosen positive direction.
What earns the marks
- States that velocity is speed in a stated direction, giving both magnitude and direction.
- Identifies velocity as a vector quantity because it has magnitude and direction.
- Distinguishes speed as scalar, having magnitude only.
- Explains that a change in direction changes velocity even when speed is constant.
- Applies the idea to examples such as circular motion or motion along a straight line with a stated positive direction.
- Interprets a negative velocity as motion opposite to the chosen positive direction.
Common mistakes and how to put them right
Treating velocity and speed as always interchangeable.
Put it right by stating that velocity requires a direction and speed does not.
Saying a body moving at constant speed in a circle has constant velocity.
Put it right by explaining that its direction changes, so velocity changes.
Ignoring direction when reading a graph or giving an answer.
Put it right by stating the direction, for example 6 m/s east or 6 m/s to the right.
Exam tips
- Always include a direction when asked for velocity, such as 'north' or 'to the left'.
- If a question asks why velocity changes, refer to a change in direction or a change in speed, not just 'it moves'.
- Use the words scalar and vector precisely: scalar means magnitude only, vector means magnitude and direction.
Try the lesson
The start of the Velocity: The velocity of an object is its speed in a given direction. Velocity is a vector quantity. lesson, made from checked teaching notes for this specification point.
Have a go first
A cyclist travels at a speed of 6 m/s due north. Which statement describes the cyclist's velocity?
Listen
Velocity describes how fast an object moves and the direction in which it moves. Speed alone gives only the magnitude, for example 8 m/s, whereas velocity adds a direction, for example 8 m/s due north. Because direction is part of the definition, velocity is a vector quantity: a change in direction changes velocity even if the speed stays constant. For example, a car going round a roundabout at a steady 10 m/s has changing velocity because its direction keeps changing. In calculations, a negative velocity indicates motion in the opposite direction to a chosen positive direction. A strong answer earns marks for these points. States that velocity is speed in a stated direction, giving both magnitude and direction. Identifies velocity as a vector quantity because it has magnitude and direction. Distinguishes speed as scalar, having magnitude only. Explains that a change in direction changes velocity even when speed is constant. A common slip: Treating velocity and speed as always interchangeable. Instead, stating that velocity requires a direction and speed does not. Exam tip: Always include a direction when asked for velocity, such as 'north' or 'to the left'.
See it
Key words
Say what each word means before you turn the card.
Velocity
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Vector quantity
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Speed
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Scalar
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See every definition
- Velocity
- The speed of an object in a given direction, and a vector quantity.
- Vector quantity
- A quantity that has both magnitude and direction, such as velocity.
- Speed
- A scalar quantity that gives only the magnitude, for example 8 m/s.
- Scalar
- A quantity that has magnitude only, without direction.
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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