Hello, I'm trying to make a wall that push an object when it hits the wall and when the wall its yellow painted.

I already made a wall that when I paint the wall with the blue color, it pull an object, but I don't know how to make pushing it when its touching.

Here's the Yellow Wall Script (it works):

using UnityEngine;   
using System.Collections;

public class NewBehaviourScript : MonoBehaviour {


public Rigidbody bola; 
public float speed = 2;


public void Update(){

}
public void OnCollisionEnter(Collision collision) 
{ 
 if (collision.gameObject.tag == ("bola")){   
 if (renderer.material.color==Color.yellow){


      Debug.Log("tocou");
  bola.transform.Translate(Vector3.forward* speed * Time.deltaTime);
        }
    }     
  } 
 }