---
title: velocity
framework: scenekit
role: symbol
role_heading: Type Property
path: scenekit/scnparticlesystem/particleproperty/velocity
---

# velocity

The particle’s velocity vector in units (of scene coordinate space) per second.

## Declaration

```swift
static let velocity: SCNParticleSystem.ParticleProperty
```

## Discussion

Discussion This property’s value is a three-component vector (an NSValue object containing an SCNVector3 value for particle property controllers, or an array of three float values for particle event or modifier blocks). The particle system’s particleVelocity and particleVelocityVariation properties determine the initial speed of each particle.

## See Also

### Type Properties

- [angle](scenekit/scnparticlesystem/particleproperty/angle.md)
- [angularVelocity](scenekit/scnparticlesystem/particleproperty/angularvelocity.md)
- [bounce](scenekit/scnparticlesystem/particleproperty/bounce.md)
- [charge](scenekit/scnparticlesystem/particleproperty/charge.md)
- [color](scenekit/scnparticlesystem/particleproperty/color.md)
- [contactNormal](scenekit/scnparticlesystem/particleproperty/contactnormal.md)
- [contactPoint](scenekit/scnparticlesystem/particleproperty/contactpoint.md)
- [frame](scenekit/scnparticlesystem/particleproperty/frame.md)
- [frameRate](scenekit/scnparticlesystem/particleproperty/framerate.md)
- [friction](scenekit/scnparticlesystem/particleproperty/friction.md)
- [life](scenekit/scnparticlesystem/particleproperty/life.md)
- [opacity](scenekit/scnparticlesystem/particleproperty/opacity.md)
- [position](scenekit/scnparticlesystem/particleproperty/position.md)
- [rotationAxis](scenekit/scnparticlesystem/particleproperty/rotationaxis.md)
- [size](scenekit/scnparticlesystem/particleproperty/size.md)