This paper deals with the study of a variable mass dynamic where is developed the Atwood machine experiment with variable mass of a resting chain in which one end is attached to a fine string which passes over a pulley and carries a weight. The damped harmonic oscillation was observed. The Newton's second law was employed to obtaining of the upward motion of the chain. Using a digital camera and free software VirtualDub it was possible to record the evolution of the space-time and to reproduce it in a number of frames in a low cost operation. Good agreement was obtained between experimental results and the predictions of the movement dynamical variables. Comparisons between these results and those obtained using expensive photogates were done. These photogates shown bad results of the measurements done at the beginning of the movement.
mechanics; movement; body free fall; digital camera
