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 coefficient of static friction is defined as the ratio of the maximum static friction force (F) between the surfaces in contact to the normal (N) force. The coefficient of kinetic friction is defined as the ratio of the kinetic friction force (F) between the surfaces in contact to the normal force: Ff/N.