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 a comparison of the density of a given material to the density of water. Water has a density of 1 gram per cubic centimeter (at 4 degrees C). That makes the math really easy. 1.93 g/cc compared to 1 g/cc equals a specific gravity of 1.93 for the clay in the brick. Note that specific gravity has no units associated with it. It's a number only. We've used mass and volume to find density, and then compared the density of our stuff to that of water to find its specific gravity. Piece of cake.