Summary: David Alciatore, PhD ("Dr. Dave") ILLUSTRATED PRINCIPLES
"Squirt, Swerve, and Throw Wrap-up"
Note: Supporting narrated video (NV) demonstrations, high-speed video (HSV) clips, and
technical proofs (TP), and all of my past articles, can be accessed and viewed online at
billiards.colostate.edu. The reference numbers used in the article help you locate the
resources on the website. If you have a slow or inconvenient Internet connection, you
might want to view the resources from a CD-ROM or DVD. See the website for details.
In case you haven't noticed, I just dedicated the last 20 articles (almost two years worth) to
squirt, swerve, and throw. I'm sure many of you are thinking: "enough, already!" Well, before
moving on to other topics, I wanted to give some examples that bring together some of the
information in a "big picture" sort of way.
Diagram 1 illustrates all of the effects that come into play when using English. To refresh
your memory, squirt, also called deflection, refers to the angular change in the initial cue ball
(CB) direction due to an off-center hit. In other words, when you use English, the CB doesn't go
where you are aiming because of squirt. The amount of squirt increases with the amount of
English. For more information, see my August `07 through March `08 articles and NV 4.13, NV
A.17, and NV B.1. The CB also swerves (curves) on its way to the object ball (OB). The amount
of swerve depends on cue elevation, shot speed, and distance between the CB and OB. For
more information, see last month's article and NV 4.14, NV 7.12, and NV B.1. Sometimes, the
phrase "effective squirt" or the term "squerve" is used to refer to the net effect of both squirt and