Bouncing Balls demonstrates a physics simulation of colorful particles colliding and bouncing within a canvas. Clicking adds new balls to the scene. The visualization uses D3’s `forceSimulation` with `forceCollide`, `forceX`, and `forceY` to handle particle interactions, while a custom `timer` loop applies gravity and wall collision logic. Rendering is done via the Canvas 2D API, with trails, velocity lines, and arrowheads colored by speed using HSL values.