For large objects sliding over one another, the friction force is proportional to the true contact area between the two bodies — this is smaller than the apparent contact area as the surfaces are rough, consisting of a large number of smaller features (asperities) that actually make contact. Here a related idea holds for contacts at the nanoscale: the friction force depends linearly on the number of atoms (rather than asperities) chemically interacting across the sliding interfaces.
- Yifei Mo
- Kevin T. Turner
- Izabela Szlufarska