# Velocity

How fast your position changes, with a direction. Average velocity is displacement divided by time.

Physics (university) · Part 01: Motion and vectors · Card 2 of 8 · Last updated 2026-10-19

## Analogy

Speed is the number on the speedometer. Velocity also says which way you are going.

## Example

**Average velocity**

v = displacement / time
v = 100 m / 20 s
v = 5 m/s east

## In practice

A runner covers 100 m east in 20 s. Her average velocity is 5 m/s east.

## Practice

### Flashcards

- **What is the difference between speed and velocity?** Speed has size only. Velocity has size and direction.

### Interview questions

**Explain why a car going round a bend at steady speed is still accelerating.**

- Acceleration is a change in velocity
- Direction changes even if speed does not
- Acceleration points toward the centre of the bend

## Questions people ask

### What is the difference between average and instantaneous velocity?

Average velocity is total displacement divided by total time for a whole trip. Instantaneous velocity is the velocity at one exact moment, like the reading you would get from a perfect speedometer that also shows direction. On a graph it is the slope at a point.

### Why is velocity measured in metres per second?

Velocity is a change in position, measured in metres, divided by the time it takes, measured in seconds. So the SI unit is metres per second. To convert from km/h to m/s, divide by 3.6. For example, 36 km/h equals 10 m/s.

## Related concepts

- [Acceleration](https://studyvisually.com/learn/science/physics-university/physics-university-part-1/physics-university-part-1-concept-3)
- [Displacement](https://studyvisually.com/learn/science/physics-university/physics-university-part-1/physics-university-part-1-concept-1)
- [Constant-acceleration equations](https://studyvisually.com/learn/science/physics-university/physics-university-part-1/physics-university-part-1-concept-4)
- [Free fall](https://studyvisually.com/learn/science/physics-university/physics-university-part-1/physics-university-part-1-concept-5)

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