  We analyse the effect of velocity and acceleration on the temperature felt by
particles and strings in backgrounds relevant in holographic models. First, we
compare accelerated strings and strings at finite temperature. We find that for
fixed Unruh temperature felt by the string endpoints, the screening length is
smaller for the accelerated Wilson loop than for the static one in a thermal
background of the same temperature; hence acceleration provides a "more
efficient" mechanism for melting of mesons. Secondly, we show that the
velocity-dependence of the screening length of the colour force, previously
obtained from a moving Wilson loop in a finite temperature background, is not
specific for the string, but is a consequence of the generic fact that an
observer which moves with constant velocity in a black hole background measures
a velocity-dependent temperature. Finally, we analyse accelerated particles and
strings in the AdS black hole background, and show that these feel a
temperature which increases as a function of time. As a byproduct of our
analysis we find a global Minkowski embedding for the planar AdS black hole.
