diff --git a/CM2030 Graphics Programming/Topic 4/4.5.1/index.html b/CM2030 Graphics Programming/Topic 4/4.5.1/index.html
index c0b3c6d..75080dd 100644
--- a/CM2030 Graphics Programming/Topic 4/4.5.1/index.html	
+++ b/CM2030 Graphics Programming/Topic 4/4.5.1/index.html	
@@ -7,8 +7,9 @@
     <script src="libraries/p5.sound.min.js" type="text/javascript"></script>
 
     <script language="javascript" type="text/javascript" src="libraries/matter.js"></script>
-    <script language="javascript" type="text/javascript" src="physics.js"></script>
     <script src="sketch.js" type="text/javascript"></script>
+    <script language="javascript" type="text/javascript" src="physics.js"></script>
+    
 
     <style> body {padding: 0; margin: 0;} canvas {vertical-align: top;} </style>
   </head>
diff --git a/CM2030 Graphics Programming/Topic 4/4.5.1/physics.js b/CM2030 Graphics Programming/Topic 4/4.5.1/physics.js
index 9fac768..3d79042 100644
--- a/CM2030 Graphics Programming/Topic 4/4.5.1/physics.js	
+++ b/CM2030 Graphics Programming/Topic 4/4.5.1/physics.js	
@@ -16,13 +16,21 @@ function drawGround(){
 ////////////////////////////////////////////////////////////////
 function setupPropeller(){
   // your code here
+  propeller = Bodies.rectangle(150, 480, 200, 15, {isStatic: true, angle: 0});
+  World.add(engine.world, [propeller]);
 }
 ////////////////////////////////////////////////////////////////
 //updates and draws the propeller
 function drawPropeller(){
+  Body.setAngle(propeller, angle);
+  Body.setAngularVelocity(propeller, angleSpeed);
   push();
-  // your code here
+  fill(255);
+  //translate(propeller.position.x, propeller.position.y);
+  //rotate(propeller.angle);
+  drawVertices(propeller.vertices);
   pop();
+  angle += angleSpeed;
 }
 ////////////////////////////////////////////////////////////////
 function setupBird(){
@@ -35,19 +43,47 @@ function setupBird(){
 ////////////////////////////////////////////////////////////////
 function drawBirds(){
   push();
-  //your code here
+  for (let i = 0; i < birds.length; i++)
+  {
+    drawVertices(birds[i].vertices);
+    if(isOffScreen(birds[i]))
+    {
+      World.remove(engine.world, birds[i]);
+      birds.splice(i, 1);
+      i--;
+    }
+  }
   pop();
+  console.log("# Birds: ", birds.length);
+  console.log("# World Bodies: ", engine.world.bodies.length);
 }
 ////////////////////////////////////////////////////////////////
 //creates a tower of boxes
 function setupTower(){
-  //you code here
+  boxes = Composites.stack(500, 100, 3, 6, 0, 0,
+    function(x,y){
+      let partA = Bodies.rectangle(x, y, 80, 80, {density: 0.001});
+      colors.push(Math.trunc(random(100, 255)));
+      return Body.create({parts: [partA]});
+    });
+  Composite.add(engine.world, [boxes]);
 }
 ////////////////////////////////////////////////////////////////
 //draws tower of boxes
 function drawTower(){
   push();
-  //your code here
+  for (let i = 0; i < boxes.bodies.length; i++) {
+    fill(0, colors[i], 0);
+    noStroke();
+    drawVertices(boxes.bodies[i].vertices);
+    if(isOffScreen(boxes.bodies[i]))
+    {
+      World.remove(engine.world, boxes.bodies[i]);
+      boxes.bodies.splice(i, 1);
+      colors.splice(i, 1);
+      i--;
+    }
+  }
   pop();
 }
 ////////////////////////////////////////////////////////////////
diff --git a/CM2030 Graphics Programming/Topic 4/4.5.1/sketch.js b/CM2030 Graphics Programming/Topic 4/4.5.1/sketch.js
index 34f82b1..a1e22f6 100644
--- a/CM2030 Graphics Programming/Topic 4/4.5.1/sketch.js	
+++ b/CM2030 Graphics Programming/Topic 4/4.5.1/sketch.js	
@@ -9,16 +9,18 @@ var Body = Matter.Body;
 var Constraint = Matter.Constraint;
 var Mouse = Matter.Mouse;
 var MouseConstraint = Matter.MouseConstraint;
+let Composites = Matter.Composites;
+let Composite = Matter.Composite;
 
 var engine;
 var propeller;
-var boxes = [];
+var boxes = null;
 var birds = [];
 var colors = [];
 var ground;
 var slingshotBird, slingshotConstraint;
 var angle=0;
-var angleSpeed=0;
+var angleSpeed=0.01;
 var canvas;
 ////////////////////////////////////////////////////////////
 function setup() {
@@ -56,10 +58,10 @@ function draw() {
 //use arrow keys to control propeller
 function keyPressed(){
   if (keyCode == LEFT_ARROW){
-    //your code here
+    angleSpeed += 0.01;
   }
   else if (keyCode == RIGHT_ARROW){
-    //your code here
+    angleSpeed -= 0.01;
   }
 }
 ////////////////////////////////////////////////////////////
@@ -93,7 +95,8 @@ function mouseReleased(){
 //tells you if a body is off-screen
 function isOffScreen(body){
   var pos = body.position;
-  return (pos.y > height || pos.x<0 || pos.x>width);
+  return (pos.y > height)
+  // Modified so bodies don't disappear when they're not completely off the screen yet
 }
 ////////////////////////////////////////////////////////////
 //removes a body from the physics world