[solved] Unity error CS0039: Cannot convert type `UnityEngine.GameObject' to `UnityEngine.Rigidbody' via a built-in conversion

if(Input.GetButtonUp("Fire1"))
            {
                Debug.Log("shoot");
                Rigidbody instance = Instantiate(bullet, transform.position, transform.rotation) as Rigidbody;
                instance.AddForce (shooter * power);
               
            }

error CS0039: Cannot convert type `UnityEngine.GameObject' to `UnityEngine.Rigidbody' via a built-in conversion

Rigidbody 선언이 에러난다. 

그러면 다른 방법 ->

if(Input.GetButtonUp("Fire1"))
            {
                Debug.Log("shoot");
                GameObject instance = Instantiate(bullet, transform.position, transform.rotation);
                instance.GetComponent<Rigidbody> ().AddForce (shooter * power);
            }

다르게 접근하자 By GetComponent