Why is the coefficient of kinetic friction generally less than the coefficient of static friction? Fk<Fs
http://en.wikipedia.org/wiki/Friction
The coefficient of kinetic friction (Fk) is generally less than the coefficient of static friction (Fs) because the surfaces in contact have already overcome the static friction and are now in motion. When an object is stationary and you try to move it, you have to apply a force to overcome the force of static friction. The coefficient of static friction is a measure of the force needed to overcome this initial resistance.
Once the object starts moving, it experiences kinetic friction, which is usually less than the static friction. Kinetic friction is the force that opposes the motion of an object once it is already in motion. This force is typically lower because the surfaces are no longer locked and are sliding past each other, causing less resistance.
To determine the value of the coefficients of friction for a specific situation or material pair, you can consult various resources such as engineering handbooks, material datasheets, or conduct experiments. These sources provide experimental data or empirical formulas for calculating friction coefficients based on specific conditions like surface roughness, temperature, and the type of materials involved. The coefficient of friction can vary between different materials and surface conditions, so it's essential to refer to specific references for accurate values.