var Engine = Matter.Engine,
        Render = Matter.Render,
        Runner = Matter.Runner,
        Body = Matter.Body,
        Composites = Matter.Composites,
        MouseConstraint = Matter.MouseConstraint,
        Mouse = Matter.Mouse,
        World = Matter.World;
    var engine = Engine.create(),
        world = engine.world;
    var render = Render.create({
        element: document.body,
        engine: engine,
        options: {
            width: 600,
            height: 400,
            showVelocity: true
        }
    });
    Render.run(render);
    var runner = Runner.create();
    Runner.run(runner, engine);
    var cradle = Composites.newtonsCradle(280, 100, 3, 30, 200);
    World.add(world, cradle);
    Body.translate(cradle.bodies[0], { 
        x: -180, 
        y: -100 
    });
    var mouse = Mouse.create(render.canvas),
        mouseConstraint = MouseConstraint.create(engine, {
            mouse: mouse,
            constraint: {
                stiffness: 0.2,
                render: {
                    visible: false
                }
            }
        });
    World.add(world, mouseConstraint);
    render.mouse = mouse;
    Render.lookAt(render, {
        min: { 
            x: 0, 
            y: 50 
        },
        max: { 
            x: 800, 
            y: 600 
        }
    });