Compute the kinetic friction force opposing sliding motion from the coefficient of kinetic friction and the normal force.
滑动摩擦力等于动摩擦系数乘正压力。
| Item | Formula | Source / Standard |
|---|---|---|
| Kinetic friction | f_k = μ_k · N | Coulomb 1785 |
| Coefficient | μ_k < μ_s usually | Amontons |
| Direction | Opposite to motion | Newton 3rd |
Constants used on this page and their authoritative sources, for verification and citation
| Constant | Value | Unit | Source |
|---|---|---|---|
| Standard acceleration of gravity g_n | 9.80665 | m·s⁻² | ISO 80000-3 / BIPM conventional value (exact) |
Note: the kinetic friction coefficient μ_k is an empirical material-pair value with no authoritative constant to cite; the Coulomb model (friction independent of apparent contact area) holds only approximately at moderate loads and speeds.