Impulse Adds Onto Brothers of Instantiation

Unity Engine
1

Hi there,
I have a script that works something like this for the iOS.

	var grenadePF : GameObject; ///prefab used to instantiate. 
	var grenade : GameObject; //remains empty in inspector. 
function Update () 
{
    if (Input.touchCount == 1) 
    {
		if(Input.GetTouch(0).phase == TouchPhase.Began) 
		{	
			grenade = Instantiate(grenadePF, bulletPos, transform.rotation); // create bullet clone 
		}
		if(Input.GetTouch(0).phase == TouchPhase.Ended) 
		{
			grenade.rigidbody.AddForce(Vector3(proDir.x, proDir.y, 0.0) * (speed * proDirDistance) * 0.002, ForceMode.Impulse);
		}
    }
}

the problem is, and I am quite sure I know why, but unsure how to fix it. The problem is, each time I create and lauch a new genade, I am either taking a grenade that already exists, or somehow the impulse power I am adding is additive, so regardless if the new grenade I am using is new or not, the speed at which the grenade launches gets faster and faster and faster.

So I need to know, how do I use a var grenade : GameObject best so that it’s impulse power is singular, and is not added up?

Essentially, how do I prevent the impulse power from passing to brothers of the same instantiated object?

2

I could use a non class var I guess but I am creating, manipulating position then launching the grenade in different functions.

Somehow I think the Impulse, is being added and added and added.