# Update

> Use this enumeration to instruct Unity to execute the physics simulation immediately after MonoBehaviour.Update().

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)
* **Assembly:** UnityEngine.PhysicsModule

```csharp
Update = 1
```

### Remarks

Executing the physics simulation during [MonoBehaviour.Update()](/engine/6000.0/script-reference/unityengine/monobehaviour/update.md) provides a less stable and deterministic physics simulation due to the unpredictable fluctuations in framerate that can arise. However, the physics simulation is always synchronized each frame, including contacts between [Collider](/engine/6000.0/script-reference/unityengine/collider.md)s. This mode doesn't require [Rigidbody](/engine/6000.0/script-reference/unityengine/rigidbody.md) interpolation.

Additional Resources: [Physics.simulationMode](/engine/6000.0/script-reference/unityengine/physics/simulationmode.md).