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.
The relative density of a solid or liquid, usually when measured at a temperature of 20Â°C, compared with the maximum density of water (at 4Â°C). For example, the specific gravity of carbon steel is 7.8, that of lead is 11.34, and that of pure gold is 19.32. specific gravity in Culture Expand.