# FixedUpdate

> Use this enumeration to specify to Unity that it should execute the physics simulation immediately after the MonoBehaviour.FixedUpdate().

## Definition

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

```csharp
FixedUpdate = 0
```

### Remarks

Executing the physics simulation during [MonoBehaviour.FixedUpdate()](/engine/6000.7/script-reference/unityengine/monobehaviour/fixedupdate.md) provides the most stable physics simulation however, Unity may render multiple frames between simulation updates. This means that changes made per-frame may not be synchronized with the physics simulation including contacts between [Collider2D](/engine/6000.7/script-reference/unityengine/collider2d.md). In this mode [Rigidbody2D](/engine/6000.7/script-reference/unityengine/rigidbody2d.md) interpolation should be used to provide smoother movement per-frame where appropriate.

Additional Resources: [Physics2D.simulationMode](/engine/6000.7/script-reference/unityengine/physics2d/simulationmode.md).