# OnCollisionEnter(Collision)

> OnCollisionEnter is called when this collider/rigidbody has begun touching another rigidbody/collider.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine](/engine/6000.5/script-reference/unityengine.md)

## OnCollisionEnter()

```csharp
public void OnCollisionEnter(Collision collision)
```

### Parameters

**** (\[Collision]\(/engine/6000.5/script-reference/unityengine/collision)): 

### Remarks

In contrast to OnTriggerEnter, OnCollisionEnter is passed the [Collision](/engine/6000.5/script-reference/unityengine/collision.md) class and not a Collider. The [Collision](/engine/6000.5/script-reference/unityengine/collision.md) class contains information, for example, about contact points and impact velocity. Notes: Collision events are only sent if one of the colliders also has a non-kinematic rigidbody attached. Collision events will be sent to disabled MonoBehaviours, to allow enabling Behaviours in response to collisions.

### Examples

```csharp

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    AudioSource audioSource;

    void Start()
    {
        audioSource = GetComponent<AudioSource>();
    }

    void OnCollisionEnter(Collision collision)
    {
        foreach (ContactPoint contact in collision.contacts)
        {
            Debug.DrawRay(contact.point, contact.normal, Color.white);
        }
        if (collision.relativeVelocity.magnitude > 2)
            audioSource.Play();
    }
}
```