# velocityOverLifetime

> Script interface for the VelocityOverLifetimeModule of a Particle System.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.7/script-reference/unityengine.md)
* **Assembly:** UnityEngine.ParticleSystemModule

```csharp
public ParticleSystem.VelocityOverLifetimeModule velocityOverLifetime { get; }
```

### Remarks

This module sets the velocity of particles during their lifetime.

Particle System modules do not need to be reassigned back to the system; they are interfaces and not independent objects.

### Examples

```csharp
using UnityEngine;
using System.Collections;

[RequireComponent(typeof(ParticleSystem))]
public class ExampleClass : MonoBehaviour {
    void Start() {
        ParticleSystem ps = GetComponent<ParticleSystem>();
        var vel = ps.velocityOverLifetime;
        vel.enabled = true;
        vel.space = ParticleSystemSimulationSpace.Local;

        AnimationCurve curve = new AnimationCurve();
        curve.AddKey(0.0f, 1.0f);
        curve.AddKey(1.0f, 0.0f);
        vel.x = new ParticleSystem.MinMaxCurve(10.0f, curve);
    }
}
```