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 is the ratio of the density of wood to the density of water. A wood doesn't float, for example, if it's specific gravity is 1.00 or greater. We display the specific gravity for each of our woods using it's kiln-dried measurement (instead of the non-dried measurement).