GetComponent ().velocity returns zero

i have a cube whose movement is controlled using arrow keys. the following image shows the componnents attached to it:

and the contents of the scripts attached to the cube is as follows:

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour {
	public float forwardSpeedMult = 5f;
	public float lateralSpeedMult = 10f;
	public Vector2          minXY; // minimum XY the cube can move to
	public Vector2          maxXY; // maximum xy the cube can move to
	public float tilt=10f;

	// Use this for initialization
	void Start () {
	void FixedUpdate () {
		float h = Input.GetAxis ("Horizontal");
		float v = Input.GetAxis ("Vertical");
		transform.position += new Vector3 (h * lateralSpeedMult * Time.deltaTime
		                                   , v * lateralSpeedMult * Time.deltaTime
		                                   , forwardSpeedMult * Time.deltaTime);
		Vector3 tPosition = transform.position;
		// Limit the X & Y to minimum and maximum values
		tPosition.x = Mathf.Clamp(tPosition.x, minXY.x, maxXY.x);
		tPosition.y = Mathf.Clamp(tPosition.y, minXY.y, maxXY.y);
		transform.position = tPosition;
		//tilting the player
		print (GetComponent<Rigidbody> ().velocity);
		GetComponent<Rigidbody>().rotation = Quaternion.Euler (0f, 0f, GetComponent<Rigidbody>().velocity.x*-tilt);

when i move the cube, the velocity of the rigidbody retuned is either zero or something like 10^-7. the cube moves but its rigidbody velocity doesnt change. it could be seen in the console in the image.

Yes you guessed right - what you do is you just take object from one place and put it in another. If you want velocity to be there then you should assign it.

Something like:

private Rigidbody playerbody;
private void Awake()
        playerbody = GetComponent<Rigidbody>();
//and then in code:
playerbody.velocity = YourVector3;

P.S. The thing with storing reference in Awake or Start (depending on expected behavior) will save you some “horse power” and will run faster than Getting component each time. Just FYI.