unity oncollisionenter

    void OnCollisionEnter2D(Collision2D col)
    {
		//This method will run when your 2D game object
      	//collides with something

      	Debug.Log("Collided");
    }

    void OnCollisionEnter(Collision col)
    {
		//This method will run when your game object
      	//collides with something

      	Debug.Log("Collided");
    }

void OnCollisionEnter(Collision collision) {
       if (collision.gameObject.tag == "Door")
       {
               // DoorScript is the name you gave to the script on the door
               DoorScript script = collision.gameObject.GetComponent<DoorScript>();
               // OpenDoor is a method in your door object's script
               script.OpenDoor();
       }
}

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();
    }
}