Summary: David Alciatore, PhD ("Dr. Dave") ILLUSTRATED PRINCIPLES
"Coriolis was brilliant ... but he didn't have a high-speed camera
Part VI: maximum rolling deflection"
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 3.8) help you locate the resources on the website.
This is the sixth and final article in a series I am writing about the pool physics book written in
1835 by the famous mathematician and physicists Coriolis. Over the past five months, I
described some high-speed camera work I've done and showed some examples that relate to
some of Coriolis' conclusions. In the last three months, I presented principles dealing with the
shape of the cue ball's path after hitting an object ball, the effect of spin and speed, the technique
required to achieve maximum English, and the system Coriolis developed for aiming massé
shots. FYI, all of my past articles can be viewed on my website in the Instructional Articles
section. This month, I look at Coriolis' conclusion concerning cue ball deflection angle for natural
roll shots, where the cue ball is rolling (i.e., not skidding or sliding) when it hits the object ball.
Diagram 1 illustrates the cut angle and deflected cue ball angle for various ball-hit fractions.
If you are unfamiliar with these terms, you should spend some time studying the diagram.
Principle 26 summarizes Coriolis' conclusion, which states that for a rolling cue ball, the final
deflected angle of the cue ball is largest (about 34°) for a cut angle slightly smaller than a half-ball
hit. People sometimes assume that the maximum deflection occurs exactly at a half-ball hit; but if