private void BallReleased_Enter () {
BallMotionController.Instance.ClearTrail ();
BeerPongInput.Instance.SetVisible (false);
ballThrowStartTime = Time.time;
Ball.GetComponent<Rigidbody> ().isKinematic = false;
Ball.GetComponent<Rigidbody>().velocity = throwDirection.normalized * MAX_VELOCITY * BeerPongInput.Instance.currentPower;
}