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, in general, is a force that makes it harder for two objects to slide alongside one another. Static friction is the friction that exists between a stationary object and the surface on which it's resting. A frictional force occurs when you try to push an object alongside a surface Once the objects have already started moving, kinetic friction takes over.