using UnityEngine;
using System.Collections;

public class ExpandAndDie : MonoBehaviour {

    public float growTime = 0.15f;
    public float initialRadius = 1.0f;
    public float finalRadius = 4.0f;


    void Start ()
    {
        StartCoroutine(GrowAndDie());
    }


    IEnumerator GrowAndDie ()
    {
        float t = 0.0f;
        Vector3 initialSize = new Vector3(initialRadius, initialRadius, initialRadius);
        Vector3 finalSize = new Vector3(finalRadius, finalRadius, finalRadius);

        while (t < growTime)
        {
            transform.localScale = Vector3.Lerp(initialSize, finalSize, t/growTime);
            t += Time.deltaTime;
            yield return null;
        }
        Destroy(gameObject);
    }
}

------------------------------------------------------


using UnityEngine;
using System.Collections;

public class AddForceOnCollision : MonoBehaviour {

    public float force = 10.0f;
    public float collisionDelay = 1.0f;


    void OnCollisionEnter (Collision other)
    {
        if (other.gameObject.tag.Contains("Player"))
        {
            other.rigidbody.AddForce (other.contacts[0].normal * force * -1.0f, ForceMode.Impulse);

            other.gameObject.SendMessage("GrenadeMoveDelay");
        }
    }
}