In this paper an experiment with plastic optical fiber to control the motion of a simple pendulum was described. The monitoring system of pendulum position is based on bend loss in plastic optical fiber which depends of bend radius. As a recording device a PC sound card was used. With this measurement technique we are able to visualize theoretical expectation and to extract some of the parameter values from the recorded data as the position, velocity and acceleration of pendulum. The angular displacements, velocity and acceleration are plotted using Mathematica, an available symbolic computer program that allows us to plot easily the obtained dependence as well as their theoretical behavior. Good agreement between measurements and theoretical prediction was observed
simple pendulum; optical fiber; PC sound card
