Jerky movement when the player is falling.

Hi!
I am experimenting a jerky movement in my current game when the player is falling, I am new in unity! so I don´t know if I am doing something wrong!.

I´ve attached a youtube video which shows the problem at the end of the video, when the character is falling down the movement is so jerky.

This is my code just in case something is wrong with it:

using UnityEngine;
using System.Collections;

public class PlayerMovement : MonoBehaviour {

public bool grounded = false;
public Transform groundedEnd;

public float speed = 6f;
public float jumpForce = 300f;

// Use this for initialization
void Start () {

}

void Update()
{
Movement();
}

void Movement()
{

//Debug.DrawLine(this.transform.position, groundedEnd.position, Color.green);
//grounded = Physics2D.Linecast (this.transform.position, groundedEnd.position, 1 << LayerMask.NameToLayer(“Platforms”));

if(Input.GetKey(KeyCode.D))
{
transform.Translate(Vector2.right * speed * Time.deltaTime);
}
if(Input.GetKey(KeyCode.A))
{
transform.Translate(-Vector2.right * speed * Time.deltaTime);
}
if (Input.GetKeyDown (KeyCode.W) )
{
rigidbody2D.AddForce(Vector2.up * jumpForce);
}

/*
currentAngle = transform.rotation.z;

if (currentAngle < .2 && !grounded)
{
transform.Rotate (Vector3.forward * 1);
}
*/

}
}

Do you use a camera script?

Instead of using Update use FixedUpdate for physics objects (ie Rigidbodies) Unity - Scripting API: MonoBehaviour.FixedUpdate()

Yes, I’m using a camera script