  In this paper we investigate the power fluctuations in a driven, dampted
pendulum. When the motion of the pendulum is chaotic, the average power
supplied by the driving force is equal to the average dissipated power only for
an infinite long time period. We measure the fluctuations of the supplied power
during a time equal to the period of the driving force. Negative power
fluctuations occur and we estimate their probability. In a chaotic state the
histogram of the power distribution is broad and continuous although bounded.
For a value of the power not too close to the edge of the distribution the
Fluctuation Theorem of Gallavotti and Cohen is approximately satisfied.
