My object moved even i havent tilt my phone...

My problem now here is when i open it in my phone my object move on its own and i havent tilt my phone.

here is my code..

vard card: GameObject; function Start () {

card = GameObject.Find("GameObject");

}

var speed: float = 10.0f;

function Update(){ var dir : Vector3 = Vector3.zero;

dir.z = -Input.acceleration.z;

if (dir.sqrMagnitude > 10)

dir.Normalize();

dir *= Time.deltaTime;

card.transform.Translate (dir * speed);

card.rigidbody.AddTorque(0, 0, 50);

card.rigidbody.AddForce(transform.forward * 50);

card.rigidbody.useGravity = true;

}