What is a variable speed drive? A variable speed drive is a piece of equipment that regulates the speed and rotational force, or torque output, of an electric motor. The background and technology. There are millions of motors in use in industry and offices around the world.
The specific gravity for Obsidian is 2.35, it's refractive index is 1.48-1.51, and it's double refraction is None. History Obsidian is named after a Roman, Obsius.
specific gravity. n. (General Physics) the ratio of the density of a substance to that of water. See relative density. specifâ²ic gravâ²ity. n. the ratio of the density of any substance to the density of a standard substance, water being the standard for liquids and solids.