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. Friction is a resistance to motion that is opposite the direction of travel. It is caused when two surfaces are in contact. Since friction acts to slow down a moving object, it is called a resistive force. This is different than active forces that cause objects to accelerate or change direction. Friction is mainly caused by surface roughness. The classic law of friction states that friction is the product of a coefficient and a force.