  We show that effects similar to those for a rotating black hole arise for an
observer using a uniformly rotating reference frame in a flat space-time: a
surface appears such that no body can be stationary beyond this surface, while
the particle energy can be either zero or negative. Beyond this surface, which
is similar to the static limit for a rotating black hole, an effect similar to
the Penrose effect is possible. We consider the example where one of the
fragments of a particle that has decayed into two particles beyond the static
limit flies into the rotating reference frame inside the static limit and has
an energy greater than the original particle energy. We obtain constraints on
the relative velocity of the decay products during the Penrose process in the
rotating reference frame. We consider the problem of defining energy in a
noninertial reference frame. For a uniformly rotating reference frame, we
consider the states of particles with minimum energy and show the relation of
this quantity to the radiation frequency shift of the rotating body due to the
transverse Doppler effect.
