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.
Lesson Summary. The specific gravity of an object is the ratio between the density of an object to a reference object. Usually, our reference object is water, which has a density of 1 g/mL or 1 g/cm^3.