  We revisit the problem of forces on atoms under current in nanoscale
conductors. We derive and discuss the five principal kinds of force under
steady-state conditions from a simple standpoint that - with the help of
background literature - should be accessible to physics undergraduates. The
discussion aims at combining methodology with an emphasis on the underlying
physics through examples. We discuss and compare two forces present only under
current - the non-conservative electron wind force and a Lorentz-like
velocity-dependent force. It is shown that in metallic nanowires both display
significant features at the wire surface, making it a candidate for the
nucleation of current-driven structural transformations and failure. Finally we
discuss the problem of force noise and the limitations of Ehrenfest dynamics.
