Collision2D.rigidbody

Description

The incoming Rigidbody2D involved in the collision with the otherRigidbody.

This may be null if the Collision2D.collider is not attached to a Rigidbody2D.

Additional resources: Collider2D and Rigidbody2D.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    void OnCollisionEnter2D(Collision2D collision2D)
    {
        //If the object we collided with was a Runner and not a Catcher.
        if (collision2D.transform.name == "Runner")
        {
            StartCoroutine(StuckInTheMud(collision2D));
        }
    }

    //Freeze the object in position for 5 seconds
    public IEnumerator StuckInTheMud(Collision2D victim)
    {
        victim.rigidbody.isKinematic = true;
        yield return new WaitForSeconds(5f);
        victim.rigidbody.isKinematic = false;
    }
}