Need some help!

Well i have this 2d game (doodle jump style) and am using the phone accelerometer, the thing is my object dont want to bounce when it collides with another object any one have a clue why?

    public float movementSpeed = 5f;

    Rigidbody2D rb;

    private void Start()
    {
        rb = GetComponent<Rigidbody2D>();
    }


    void Update()
    {
        {
            AccelerometerMove();
        }

    }

    void AccelerometerMove()
    {
        float x = Input.acceleration.x;
        Debug.Log("x =" + x);
        if (x < -0.1f)
        {
            MoveLeft();
        }
        else if (x > 0.1f)
        {
            MoveRight();
        }

    }

    public void MoveLeft()
    {
        rb.velocity = new Vector2(-movementSpeed, 0);
    }

    public void MoveRight()
    {
        rb.velocity = new Vector2(movementSpeed, 0);
    }



}

watch the video from 2:00
_**https://www.youtube.com/watch?v=23HEMKfMKKk**_