|Cutnell, John & Johnson, Kenneth. Physics, Fourth Edition. Wiley, 1998: 204.||"[diagram] m1 = 0.150 kg … m2 = 0.260 kg"||0.15 kg
|Young, Curtis. Physics of Billiards.||"15 balls are used and one cue ball, the cue ball is used to hit the remaining balls into the pockets. On average, the balls are 2.25 inches in diameter and all balls weigh 5.5 oz except or the cue,which weighs 6 oz."||0.16 kg
|BCA Equipment Specification. Billiard Congress of America.||"Pocket Billiard Balls
Weight: 5 ½ to 6 oz. *Diameter: 2 ¼
*Diameter tolerance of (plus or minus) .005"
|Encyclopedia Britannica. Eleventh Edition. Vol. 3- 4, 1910.||"The size that is generally used in matches has a diameter of 2 1/16 in., and the weight about 4 ¾ oz."||0.13 kg|
|Kanov, Gerry & Stauch, Shari. "Precision Pool." Human Kinetics, 1999.||"The standard size of a pocket ball is 2¼ inches in diameter, with a weight of six ounces."||0.17 kg|
The history of billiards in unknown. There are reports dating saying it was invented in St. Augustine by the Spaniards in the late 1500s but that has not been actually proven. Billiards however became popular in England where it was first played by royalty only. Then as the game started gaining popularity, the game moved from the higher class people to the lower and middle class people undergoing many changes as it did. The game was eventually brought over to America in the early 1770s where it quickly gained popularity and it became one of America's favorite pastimes.
There are many different variations of billiards. The most popular however are 8-ball and 9-ball. In 8-ball, there are 15 balls number 1-7 (solids) and 9-15 (stripes) and one cue ball which is meant to hit all the other balls into holes in the table called pockets. The cue ball usually weigh 0.17 kg (6 ounces) while all the other balls usually weighs 0.16 kg (5.5 ounces). At the start of the game, all the numbered balls are racked together at the edge of the table and a player has to break it which is hit all the numbered ball with the cue ball with the hopes of pocketing one or more. The object of the 8-ball is to pocket either all the solid balls or the striped balls and then pocket the 8-ball last hence the name 8-ball.
In 9-ball, instead of 15 balls, there are only 9 numbered balls plus the cue ball. The game starts out like 8-ball where all the numbered balls are racked together and a player has to break the balls. However, the object of the game is to pocket all the balls starting with the 1-ball and then moving up in order. The game ends when the 9-ball is pocketed.
For anyone who thinks that billiards is just a game that anyone can play, just pick up a cue stick and play a game and you'll be amazed to discover how fun and hard billiards can really be.
Oluwole Owoseni -- 2004