What is the difference between static friction coefficient and kinetic friction coefficient?

Answer 1

Coefficient of friction is drag. It is what keeps your feet from sliding on the floor like on ice. Inertia doesn't even have to be touching anything. In outer space anything with mass would remain still or in motion if not acted on by an outside force.

Answer 2

• First let us define Friction. Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
• The friction resisting the relative motion of solid surfaces is called dry friction.
• When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into heat.
• Friction is not itself a fundamental force but arises from fundamental electromagnetic forces between the charged particles constituting the two contacting surfaces.
• The two types of dry friction are 'static friction' between non-moving surfaces, and kinetic friction (sometimes called sliding friction or dynamic friction) between moving surfaces.
• The Coulomb friction may take any value from zero up to , where is the coefficient of friction, which is an empirical property of the contacting materials, and is the normal force exerted by each surface on the other, directed perpendicular (normal) to the surface.
• The direction of the frictional force against a surface is opposite to the motion that surface would experience in the absence of friction.
• Thus, in the static case, the frictional force is exactly what it must be in order to prevent motion between the surfaces; it balances the net force tending to cause such motion. In this case, rather than providing an estimate of the actual frictional force, the Coulomb approximation provides a threshold value for this force, above which motion would commence. This maximum force is known as traction.
• The force of friction is always exerted in a direction that opposes movement (for kinetic friction) or potential movement (for static friction) between the two surfaces. For example, a curling stone sliding along the ice experiences a kinetic force slowing it down. For an example of potential movement, the drive wheels of an accelerating car experience a frictional force pointing forward; if they did not, the wheels would spin, and the rubber would slide backwards along the pavement. Note that it is not the direction of movement of the vehicle they oppose, it is the direction of (potential) sliding between tire and road