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''.
The model also enables the manipulation of friction by selecting certain surface materials or materials used in lubrication layers, on the basis of the surface energy between them. Friction is the resistive force acting between bodies that tends to oppose and damp out motion.