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]
Curling Curling brushes may have fabric, hog hair, or horsehair heads. Modern curling brush handles are usually hollow tubes made of fibreglass or carbon fibre instead of a solid length of wooden dowel. These hollow tube handles are lighter and stronger than wooden handles, allowing faster sweeping and also enabling more downward force to be applied to the broom head with reduced shaft flex. New, "directional fabric" brooms, which players are worried will alter the fundamentals of the sport by reducing the level of skill required, have been accused of giving players an unfair advantage.[40] The new brooms were temporarily banned by the World Curling Federation and Curling Canada[41] for the 2015â€“2016 season. The new brooms give sweepers unprecedented control over the direction the stone goes.[42]