Summary: David Alciatore, PhD ("Dr. Dave") ILLUSTRATED PRINCIPLES
"Coriolis was brilliant ... but he didn't have a high-speed camera
Part III: Cue Ball Paths are Like Satellite Dishes"
Note: Supporting narrated video (NV) demonstrations, high-speed video (HSV) clips, and
technical proofs (TP) can be accessed and viewed online at billiards.colostate.edu. The
reference numbers used in the article (e.g., NV 4.20) help you locate the resources on the
This is the third article in a series I am writing about the pool physics book written by the
famous mathematician and physicists Coriolis in 1835. In last month's article, I described some
high-speed camera work I've done and showed some examples that relate to some of Coriolis'
conclusions. Over the next few months, I will look at Coriolis' conclusions in more detail and
explain when they do and don't apply. As with all of my past articles, my July '05 article
summarizing Coriolis' conclusions can be viewed on my website.
Principle 23 summarizes one of Coriolis' conclusions, which states that the cue ball's path
curves in the shape of a parabola after hitting an object ball with follow or draw (see Diagram 1).
Interestingly, a parabolic curve is the same shape used to make radio telescopes, satellite TV
dishes, and headlight mirrors. As with all of Coriolis' work, he backed up all of his results with
rigorous physics and mathematical analysis. For the sadistic readers out there with math and
physics backgrounds, you can check out the nitty-gritty details of Principle 23 at TP A.4. There I
present and illustrate the derivation with modern terminology and techniques and show plots of