already pointed out, there will be a compression
) travelling down the rod when you move it.
The velocity at which this happens (and thus the limiting speed for
communication) will be the speed of sound
in the material the rod
is made from. This will definitely be a lot
slower than the
speed of light
; for instance the speed of sound
are approximately 5100 m/s.
For example, hit a nail with a hammer; it will still take a
fraction of a second before the tip "knows" that it should move.