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Re: pool table physics - revisited



I visited a pool table store to ask about sizes.
The proprietor of "Pool Tables Plus, Inc"
mentioned that good tables all have slate beds for stability, and
come in various sizes between 6 and 9 feet long.

I measured several full size tables' cushion height: it was
1.5 to 1.6 inches above the baize.
"Baize" ('coarse woolen stuff with long nap used
for coverings') is not a term familiar in the business: 'felt'
(which strictly implies an unwoven mat) or 'billiard cloth' are
the terms in use.
Brunswick, a major maker, offers a 'superspring' cushion material.
The cushions appear to be rubber mouldings.

For a ball of 1.125 inch radius, the cushion seems to sit between
0.42 radius, and 0.33 radius above center.

This seems to fit quite well with Ben Crowell's analysis, so I suppose
the ball/cushion combinations which he measured (and which gave
rise to his concern) were atypical.

Brian

At 11:55 4/23/01 -0500, Tom Carter wrote:
Herb,

I actually the question about the size and
weight of que balls a while back when I was working
out an example problem for my class. I sent out a few
Emails. Here is the words of "the experts"

Blache Quenville of "qball.com" replied:

"To answer your questions, a standard cue ball for
American pool games weighs 6 oz. and has a diameter of 2.25",
which is true for all balls in the set. The only exception
would be on a coin-operated commercial pool table, where the
cue ball must be different so that it will not fall into
the same area as the other balls. In this case the cue ball
can be 2.25" and heavier (because it has a metal core) or
2-3/8" (also heavier)."

Don Wright of the Billiard Congress of America replied:

"BCA Specifications as follows:
Molded and finished in a perfect sphere in the following
weight and diameter
Pocket Billiard Balls
Weight: 5 1/2 to 6 oz..............*Diameter: 2 1/4"
*Diameter tolerance +or- .005"


tom


---------------------------------
Dr. Tom Carter
Physics
College of Dupage
(o) 630-942-3346
(f) 630-942-2759
http://www.cod.edu/people/faculty/cartert


-----Original Message-----
From: Herbert H Gottlieb [mailto:herbgottlieb@JUNO.COM]
Sent: Monday, April 23, 2001 8:02 AM
To: PHYS-L@lists.nau.edu
Subject: Re: pool table physics


On Mon, 23 Apr 2001 08:33:24 -0500 Clarence Bennett
<bennett@OAKLAND.EDU>
writes:
I think that in the case of coin operated pool tables, the cue ball
is slightly larger than the others, so that it can be
retrieved after
a scratch.

Does this mean that each of the pool table holes only allows the
smaller balls to fit through and the larger cue ball can
never sink into
a hole??
If so how much larger must be the cue ball so it can be easily
retrieved after a scratch?



brian whatcott <inet@intellisys.net> Altus OK
Eureka!