what are the physical properties of a baseball?
The ball comprises a rubber or cork center wrapped in yarn and covered with white horsehide or cowhide. A regulation baseball is 9–​9 1⁄4 inches (229–235 mm) in circumference (​2 55⁄64–​2 15⁄16 in. or 73–75 mm in diameter), with a mass of 5 to ​5 1⁄4 oz.