As the speed interval changes, the ball will appear to move faster. Along with speed, the rate at which the ball moves to the right, can also effect 'speed', as can the drop, down motion. For instance, if you turn the speed and both right, and down to max, (set in the code), the ball will appear to be zipping diagonally across the screen. Consider the speed a framrate, and the drop/right motions as the direction.
Ball will begin at the top left of this page, moving slowly at a diagonal angle
This was an experiment to play with animation with javascript. See the blog post here: