error CS1061: Type `PlayerPhysics' does not contain a definition for `Move' and no extension method `Move' of type `PlayerPhysics' could be found (are you missing a using directive or an assembly reference?)

What the heck is this? What kind of error asks me a question?(rhetorical) well here is my script.

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour {

	public float speed = 8;
	public float acceleration = 12;

	private float currentSpeed;
	private float targetSpeed;
	private Vector2 amountToMove;

	private PlayerPhysics playerPhysics;

	// Use this for initialization
	void Start () {
		playerPhysics = GetComponent<PlayerPhysics>();

	// Update is called once per frame
	void Update () {
		targetSpeed = Input.GetAxisRaw ("Horizontal") * speed;
		currentSpeed = IncrementTowards (currentSpeed, targetSpeed, acceleration);

		amountToMove = new Vector2 (currentSpeed, 0);
		playerPhysics.Move (amountToMove * Time.deltaTime); //this is the line it says

	private float IncrementTowards(float n, float target, float speed) {
		if (n == target) {
			return 0;
				} else {
						float dir = Mathf.Sign (target - n);
						n += Time.deltaTime * dir;
						return (dir == Mathf.Sign (target - n)) ? n : target;

According to the compiler, the PlayerPhysics class (which you don’t show), does not have a ‘Move’ method. You need to look at the PlayerPhysics class what is going on. If it does have a ‘Move’ method, search your project to see if you have more than one PlayerPhysics script.