# Velocity

Speed in a stated direction. It is a vector, so changing direction changes velocity even if the speed stays the same.

Physics (school) · Part 01: Motion and measurement · Card 4 of 8 · Last updated 2026-10-19

## Analogy

Speed is what the speedometer shows. Velocity also needs the compass.

## Example

**Bus there and back**

Bus drives east at 10 m/s.
Then it drives west at 10 m/s.
Speed stays 10 m/s.
Velocity goes from +10 to -10 m/s.

## In practice

A car going round a roundabout at steady speed is still accelerating, because its direction keeps changing.

## Practice

### Flashcards

- **What is the difference between speed and velocity?** Velocity is speed in a given direction. Speed has no direction.

## Questions people ask

### Can an object have constant speed but changing velocity?

Yes. Velocity includes direction, so turning changes it. A car driving round a bend at a steady 20 m/s keeps the same speed, but its direction changes all the time. That means its velocity is changing, which is the same as saying it is accelerating.

### Why can velocity be negative?

The sign shows direction. Pick one direction as positive, for example east. An object moving the opposite way has a negative velocity. The minus sign does not mean slower. A velocity of -10 m/s is exactly as fast as +10 m/s, just heading the other way.

## Related concepts

- [Scalar and vector](https://studyvisually.com/learn/science/physics-school/physics-school-part-1/physics-school-part-1-concept-2)
- [Speed](https://studyvisually.com/learn/science/physics-school/physics-school-part-1/physics-school-part-1-concept-3)
- [Distance-time graph](https://studyvisually.com/learn/science/physics-school/physics-school-part-1/physics-school-part-1-concept-5)
- [Acceleration](https://studyvisually.com/learn/science/physics-school/physics-school-part-1/physics-school-part-1-concept-6)

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