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 of a metal or alloy is merely the weight in grams of one cubic centimeter. When it is more convenient to work in troy weights, the number of ounces per cubic inch of any metal or alloy may be found by multiplying its specific gravity by the constant 0.52686.