2. The coefficient of kinetic friction
varies with the type of surface.
• Smoother surfaces are more slippery.
• Just think about sliding across these surfaces:
– A shag carpet
– A freshly waxed hardwood floor
– An ice rink
• The more slippery the surface, the less the
coefficient of friction is for it.
3. Common Coefficients
Materials Kinetic Friction
coefficient, µ
Rubber on concrete 0.80
Steel on steel (dry) 0.60
Steel on steel 0.05
(lubricated)
Wood on wood 0.20
Wood on snow 0.06
Ice on ice 0.03