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 and Area of Contact. Part of the standard model of surface friction is the assumption that the frictional resistance force between two surfaces is independent of the area of contact. While exceptions exist, the assumption has enough validity to be useful in many circumstances.