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. Specific gravity is defined in Webster's dictionary as the ratio of the weight or mass of a given volume of a substance to that of another substance (usually water for solids and liquids) used as a standard. Specific gravity is not expressed in units as it is purely a ratio. Density Table.