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''.
In conclusion. Friction is a force resisting motion of an object when in contact with another. It is caused by the surface roughness of the contact area of the materials, deformations or the molecular attraction. The standard friction equation holds for hard objects being held back by surface roughness.