how heavy are the stones in olympic curling
Curling The curling stone (also sometimes called a rock in North America) is made of granite and is specified by the World Curling Federation, which requires a weight between 38 and 44 pounds (17.24 and 19.96 kg), a maximum circumference of 36 inches (914.4 mm) and a minimum height of 4.5 inches (114.3 mm).[30] The only part of the stone in contact with the ice is the running surface, a narrow, flat annulus or ring, 0.25 to 0.50 inches (6.4 to 12.7 mm) wide and about 5 inches (130 mm) in diameter; the sides of the stone bulge convex down to the ring and the inside of the ring is hollowed concave to clear the ice. This concave bottom was first proposed by J. S. Russell of Toronto, Ontario, Canada sometime after 1870, and was subsequently adopted by Scottish stone manufacturer Andrew Kay.[23]
Stone (unit) The name "stone" derives from the use of stones for weights, a practice that dates back into antiquity. The Biblical law against the carrying of "diverse weights, a large and a small"[7] is more literally translated as "you shall not carry a stone and a stone (אבן ואבן), a large and a small". There was no standardised "stone" in the ancient Jewish world,[8] but in Roman times stone weights were crafted to multiples of the Roman pound.[9] Such weights varied in quality: the Yale Medical Library holds 10 and 50-pound examples of polished serpentine,[10] while a 40-pound example at the Eschborn Museum (see right) is made of sandstone.[11]