4.
Coefficients of Friction
Here are some examples of coefficients of static and kinetic friction. Generally speaking, the "slipperier" the surfaces are against each other, the smaller the coefficients.System | Static friction $\mu_S$ | Kinetic friction $\mu_K$ |
Teflon on steel | 0.04 | 0.04 |
Steel on steel (oiled) | 0.05 | 0.03 |
Shoes on ice | 0.1 | 0.05 |
Ice on ice | 0.1 | 0.03 |
Waxed wood on wet snow | 0.14 | 0.1 |
Steel on ice | 0.4 | 0.02 |
Wood on wood | 0.5 | 0.3 |
Metal on wood | 0.5 | 0.3 |
Steel on steel (dry) | 0.6 | 0.3 |
Rubber on wet concrete | 0.7 | 0.5 |
Shoes on wood | 0.9 | 0.7 |
Rubber on dry concrete | 1.0 | 0.7 |