var ArenaCircle = Container.expand(function () {
	var self = Container.call(this);
	self.radius = 2048 * 0.4;
	var circleGraphics = self.createAsset('arenaCircle', 'Arena Circle Graphics', 0.5, 0.5);
	var orbitLine = self.createAsset('orbitLine', 'Orbit Line Graphics', 0.5, 0.5);
	circleGraphics.width = self.radius * 2;
	circleGraphics.height = self.radius * 2;
	orbitLine.width = self.radius * 2;
	orbitLine.height = 10;
	orbitLine.tint = 0xFFFFFF;
	self.addChild(circleGraphics);
	self.addChild(orbitLine);
	self.x = 2048 / 2;
	self.y = 2732 / 2;
});
var Ball = Container.expand(function (arenaRadius, paddle) {
	var self = Container.call(this);
	Ball.prototype.intersectsBounds = function (boundsA, boundsB) {
		return boundsA.x < boundsB.x + boundsB.width && boundsA.x + boundsA.width > boundsB.x && boundsA.y < boundsB.y + boundsB.height && boundsA.y + boundsA.height > boundsB.y;
	};
	self.paddle = paddle;
	Ball.prototype.bounceOffArenaEdge = function (paddleAngle, paddleSpeed) {
		var ballAngle = Math.atan2(this.velocity.y, this.velocity.x);
		var angleDifference = 2 * (paddleAngle - ballAngle);
		var speed = Math.sqrt(this.velocity.x * this.velocity.x + this.velocity.y * this.velocity.y);
		this.velocity.x = speed * Math.cos(ballAngle + angleDifference);
		this.velocity.y = speed * Math.sin(ballAngle + angleDifference);
	};
	Ball.prototype.isCollidingWithArenaEdge = function (arenaCircle) {
		var dx = this.x - 2048 / 2;
		var dy = this.y - 2732 / 2;
		var distance = Math.sqrt(dx * dx + dy * dy);
		return distance + this.width / 2 > arenaCircle.radius;
	};
	var ballGraphics = self.createAsset('ball', 'Ball Graphics', 0.5, 0.5);
	var angleToPaddle = Math.atan2(100 - 2732 / 2, 2048 / 2 - 2048 / 2);
	self.velocity = {
		x: 5 * Math.cos(angleToPaddle),
		y: 5 * Math.sin(angleToPaddle)
	};
	self.radius = arenaRadius;
	self.move = function (arenaCircle) {
		this.x += this.velocity.x;
		this.y += this.velocity.y;
		if (this.isCollidingWithArenaEdge(arenaCircle)) {
			this.bounceOffArenaEdge(this.paddle.angle, this.paddle.speed);
		} else if (this.isCollidingWithPaddle(this.paddle)) {
			this.bounceOffPaddle(this.paddle);
		}
	};
	Ball.prototype.checkArenaCollision = function (paddle, arenaCircle) {
		if (this.isCollidingWithArenaEdge(arenaCircle)) {
			this.bounceOffArenaEdge(paddle.angle, paddle.speed);
		} else if (this.isCollidingWithPaddle(paddle)) {
			this.bounceOffPaddle(paddle);
		}
	};
	Ball.prototype.isCollidingWithPaddle = function (paddle) {
		if (paddle) {
			if (paddle) {
				var paddleBounds = paddle.getBounds();
				var ballBounds = this.getBounds();
				return paddleBounds && ballBounds && this.intersectsBounds(paddleBounds, ballBounds);
			}
		}
		return false;
	};
	Ball.prototype.bounceOffPaddle = function (paddle) {
		var angleToPaddleCenter = Math.atan2(paddle.y - this.y, paddle.x - this.x);
		var speed = Math.sqrt(this.velocity.x * this.velocity.x + this.velocity.y * this.velocity.y);
		this.velocity.x = speed * Math.cos(angleToPaddleCenter);
		this.velocity.y = -speed * Math.sin(angleToPaddleCenter);
	};
	self.reset = function () {
		self.x = 2048 / 2;
		self.y = 2732 / 2;
		var initialAngle = Math.random() * 2 * Math.PI;
		self.velocity = {
			x: 5 * Math.cos(initialAngle),
			y: 5 * Math.sin(initialAngle)
		};
	};
});
var Paddle = Container.expand(function (arenaRadius) {
	var self = Container.call(this);
	var paddleGraphics = self.createAsset('paddle', 'Paddle Graphics', 0.5, 0.5);
	self.addChild(paddleGraphics);
	self.angle = 0;
	self.radius = arenaRadius;
	self.speed = 0.05;
	self.move = function () {
		this.updatePosition();
	};
	Paddle.prototype.updatePosition = function () {
		self.angle += self.speed;
		self.x = self.radius * Math.cos(self.angle) + 2048 / 2;
		self.y = self.radius * Math.sin(self.angle) + 2732 / 2;
	};
	self.reverseDirection = function () {
		self.speed *= -1;
	};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	self.updateScore = function () {
		var currentScore = scoreTxt.text ? parseInt(scoreTxt.text.toString(), 10) : 0;
		scoreTxt.setText((currentScore + 1).toString());
	};
	LK.stageContainer.setBackgroundColor(0x000000);
	var arenaCircle = self.addChild(new ArenaCircle());
	var paddle = self.addChild(new Paddle(arenaCircle.radius));
	paddle.x = 2048 / 2;
	paddle.y = 100;
	var ball = self.addChild(new Ball(arenaCircle.radius, paddle));
	ball.reset();
	var scoreTxt = new Text2('0', {
		size: 150,
		fill: "#ffffff"
	});
	scoreTxt.anchor.set(.5, 0);
	LK.gui.topCenter.addChild(scoreTxt);
	var isGameOver = false;
	LK.on('tick', function () {
		paddle.move();
		ball.move(arenaCircle);
		var ballDistance = Math.sqrt(Math.pow(ball.x - 2048 / 2, 2) + Math.pow(ball.y - 2732 / 2, 2));
		if (ballDistance - ball.width / 2 > arenaCircle.radius) {
			LK.showGameOver();
		} else {
			self.updateScore();
		}
	});
	stage.on('down', function (obj) {
		paddle.reverseDirection();
	});
});

===================================================================
--- original.js
+++ change.js
@@ -66,10 +66,11 @@
 		return false;
 	};
 	Ball.prototype.bounceOffPaddle = function (paddle) {
 		var angleToPaddleCenter = Math.atan2(paddle.y - this.y, paddle.x - this.x);
-		this.velocity.x = -this.velocity.x * Math.cos(angleToPaddleCenter);
-		this.velocity.y = -this.velocity.y * Math.sin(angleToPaddleCenter);
+		var speed = Math.sqrt(this.velocity.x * this.velocity.x + this.velocity.y * this.velocity.y);
+		this.velocity.x = speed * Math.cos(angleToPaddleCenter);
+		this.velocity.y = -speed * Math.sin(angleToPaddleCenter);
 	};
 	self.reset = function () {
 		self.x = 2048 / 2;
 		self.y = 2732 / 2;