  We calculate tangential forces applied to a ground state atom (nanoparticle)
moving with nonrelativistic velocity parallel to the surface of Drude -modelled
or Lorentz -modelled half -space using the formalism of fluctuation
electrodynamics.The obtained formulae assume the nonretarded regime and
arbitrary temperatures of the particle and medium. The quantum frictional force
is realized at zero temperature of the particle and medium and can reach about
1/3 of the static value of the Casimir -Polder force in the case of ground
state atom. In the case of nanoparticles and nonzero temperature, the
tangential forces appears to be both frictional and accelerating. Numerical
examples are given for atoms of Na above the surface of Au and MgO
nanoparticles above the surface of SiC.
