Coefficients of friction
The coefficients μs (static) and μk (kinetic) for common pairs of materials. Static friction is the largest force that can act before sliding starts, and kinetic friction acts while it slides; μk is almost always smaller than μs. The values are approximate, given to one or two digits, and change with the state of the surfaces, dirt, moisture and load. Where two textbooks give different values for the same pair, both rows are shown.
| Pair of materials | μs | μk |
|---|---|---|
| Rubber on dry concrete | 1 | 0.7 |
| Rubber on wet concrete, lower end of the range | 0.5 | 0.3 |
| Rubber on wet concrete, upper end of the range | 0.7 | 0.5 |
| Wood on wood | 0.5 | 0.3 |
| Metal on wood | 0.5 | 0.3 |
| Shoes on wood | 0.9 | 0.7 |
| Waxed wood on wet snow | 0.14 | 0.1 |
| Steel on steel, dry | 0.6 | 0.3 |
| Steel on steel, oiled | 0.05 | 0.03 |
| Teflon on steel | 0.04 | 0.04 |
| Shoes on ice | 0.1 | 0.05 |
| Ice on ice | 0.1 | 0.03 |
| Steel on ice | 0.04 | 0.02 |
| Bone lubricated by synovial fluid | 0.016 | 0.015 |
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Sources
(2)
- OpenStax, University Physics Volume 1 (Moebs, Ling, Sanny), §6.2 Friction, Table 6.1 Approximate Coefficients of Static and Kinetic Friction (Published 19 Sep 2016) — checked October 19, 2026
- OpenStax, College Physics 2e (Urone, Hinrichs), §5.1 Friction, Table 5.1 Coefficients of Static and Kinetic Friction (Published 13 Jul 2022) — checked October 19, 2026