private bool shouldBeDestroyedByProjectileCollisionWith(Collider aCollider, float impactForce)
 {
     return(aCollider.gameObject.tag == "Rock" && impactForce >= 13f &&
            !slingshot.LaunchedThisProjectile(aCollider.gameObject) && impactIsCloseEnoughToImpactPoint(aCollider, impactForce));
 }