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# particleFriction

The friction coefficient of each particle in the system. Animatable.

```
var particleFriction: CGFloat { get set }
```

## Discussion

Friction determines a particle’s resistance to sliding motion after a collision. (To define collision behavior, see the [`colliderNodes`](/documentation/SceneKit/SCNParticleSystem/colliderNodes) property.) You can randomize the friction coefficients of particles in the system with the [`particleFrictionVariation`](/documentation/SceneKit/SCNParticleSystem/particleFrictionVariation) property.

A value of `1.0` (the default) allows a particle to slide freely, and a value of `0.0` prevents a particle from sliding.

You can animate changes to this property’s value. See [Animating SceneKit Content](/documentation/SceneKit/animating-scenekit-content).

---

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