Playing equipment
How much do squash balls weigh?
Squash (sport)
Achievement ideology Real tennis Carved Stone Balls Urban golf Johnny darter
Achievement_ideology-Need_Achievement_theory Real_tennis-Equipment Carved_Stone_Balls-Platonic_solids Urban_golf-Balls Johnny_darter-Size
Social scientists who advocate this theory believe that one’s achievement is a product of the motivation to succeed times the motivation to avoid failure. This means that individuals weigh their expectancy of success with the value they place on that success, or, how well an individual thinks s/he can do and how much doing well actually matters. 
Unlike the latex-based technology underlying the modern lawn-tennis ball, the game still utilizes a cork-based ball very close in design to the original balls used in the game. The diameter balls are handmade and consist of a core made of cork with fabric tape tightly wound around it and covered with a hand-sewn layer of heavy, woven, woollen cloth, traditionally "Melton" cloth (not felt, which is unwoven and not strong enough to last as a ball covering). The balls are traditionally white, but around the end of the 20th century "optic yellow" was introduced for improved visibility, as was done years earlier in lawn tennis. The balls are much less bouncy than lawn tennis balls, and weigh about (lawn tennis balls typically weigh 2 ounces). The long racquets are made of wood and use very tight strings to cope with the heavy balls. The racquet head is bent slightly to make it easier to strike balls close to the floor or in corners, and to facilitate a fast shot with a low trajectory that is difficult for an opponent to return. There are only two companies in the world hand-crafting these racquets: Grays of Cambridge (UK) and Harrow Sports (US) based in Denver, Colorado. 
The Carved Stone Balls have been taken as evidence of knowledge of the five Platonic solids a millennium before Plato described them. Indeed, some of them exhibit the symmetries of Platonic solids, but the extent of this and how much it depends on mathematical understanding is disputed, as configurations resembling the solids can naturally arise when placing knobs around a sphere. [http://www.neverendingbooks.org/index.php/the-scottish-solids-hoax.html] There does not appear to be much special attention given to the Platonic solid arrangements over less symmetrical arrangements of knobs over the balls, and some of the five solids do not appear. 
Balls used in urban golf vary relative to each organization and context. Although real golf balls are used in some circumstances where risk from injury is low, other balls used are Tennis Balls, Squash Balls, almostGOLF Point3 balls (used by Urban Golf associations throughout Belgium), Air Flow Balls, Cayman Balls and many types of adapted or customized balls. Shoreditch Golf Club produces and manufactures its own design of ball specifically for this game. 
Physical description. The johnny darter has an average length between 1.5 and 2.5 inches. The males are generally longer than the females; males can reach up to 3.0 inches and the females do not get much longer than 2.3 inches. Males weigh a little over 2.0 grams, and the females weigh about 1.6 grams. 