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''.
However, the frictional force for sliding contact will be lower. The ratio of the limiting frictional force to the normal force for no slipping is called the static coefficient. of friction. For sliding surfaces, the term dynamic coefficient of friction is used.