  We derive general expressions for the free energy, entropy production and
entropy extraction rates for a Brownian particle that walks in a viscous medium
where the dynamics of its motion is governed by the Langevin equation. It is
shown that when the system is out of equilibrium, it constantly produces
entropy and at the same time extracts entropy out of the system. Its entropy
production and extraction rates decrease in time and saturate to a constant
value. In long time limit, the rate of entropy production balances the rate of
entropy extraction and at equilibrium both entropy production and extraction
rates become zero. Moreover, considering different model systems, not only we
investigate how various thermodynamic quantities behave in time but also we
discuss the fluctuation theorem in detail.
