How to realize the real world physics?

/ Mouse Throw Physics by save Attach this script to a GameObject you would like to throw Last modified 2012-03-12 /

@script RequireComponent(Rigidbody) @script RequireComponent(Collider)

var strength : int = 20; //The strength to multiply in AddForce var AlterUseOfGravity : boolean = true; //If useGravity is off and AlterUseOfGravity is off the object will continue to float

static var cam : Camera; static var cameraTransform : Transform;

private var myTransform : Transform; private var myRigidbody : Rigidbody;

private var myMagnitude : Vector3 = Vector3.zero; private var initialPosition : Vector3; private var setZdepth : float = .0;

private var activated : boolean = false;

function Awake () { if (cam==null || cameraTransform==null) { cam = Camera.main; cameraTransform = cam.transform; } }

function Start () { myTransform = transform; myRigidbody = rigidbody; initialPosition = myTransform.position; }

function Update () { if (activated) { SetPosition(); } }

function SetPosition () { if (!myRigidbody.isKinematic) { myRigidbody.isKinematic = true; if (AlterUseOfGravity) myRigidbody.useGravity = false; setZdepth = myTransform.position.z-cameraTransform.position.z; }

 var pos : Vector3;
 pos = Input.mousePosition;
 pos.x = Mathf.Clamp(pos.x, 0, Screen.width);
 pos.y = Mathf.Clamp(pos.y, 0, Screen.height);
 var newPos : Vector3 = Camera.main.ScreenToWorldPoint(Vector3(pos.x, pos.y, setZdepth));
 myTransform.position = newPos;  

 myMagnitude = (myTransform.position - initialPosition) /Time.deltaTime;

 initialPosition = myTransform.position;

 if (Input.GetMouseButtonUp(0)) {
     AddForce(myMagnitude);
 }

}

function OnMouseDown () { activated = true; }

function AddForce (m : Vector3) { myRigidbody.isKinematic = false; if (AlterUseOfGravity) myRigidbody.useGravity = true; myRigidbody.AddForce(m*strength); activated = false; }