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 specific gravity is the density of the substance divided by the density of water, so. So we divide the basalt (210 lbs/ft3) by the density of water (62.4 lbs/ft3), and get S.G.= 3.37.