Agate is good protective energy stone, especially for children, and is very calming and soothing. It also can help strengthen the body's connection to the earth.
The friction factor, f, is a dimensionless factor that depends primarily on the velocity u, diameter D, density Ï, and viscosity Î·. It is also a function of wall roughness which depends on the size Îµ, spacing Îµ' and shape of the roughness elements characterized by Îµ''.
Friction is a force that opposes motion and wastes energy. Some of the energy used to create the forces that move objects is also used to overcome oppositional forces due to friction. Friction reduces the efficiency of machines and mechanisms, and good designers are always looking for ways to minimize friction.