public function moveRight($distance) 
    {
        // Ortogonal direction vector
        $rx = -$this->ry;
        $ry = $this->rx;
        
        $multiplier = $distance / sqrt($rx * $rx + $ry * $ry);

        $this->Px += $rx * $multiplier;
        $this->Py += $ry * $multiplier;
    }