Production of stroboscopic photographs without the use of a stroboscopic lamp

Most High School Physics programs begin with the study of motion. In order to understand the basic concepts it is necessary to quantify phenomena, which is not trivial, so, seldom used in the school classroom. Within the techniques that allow the necessary precise time measurements, the stroboscopic photography has been a good solution, in spite of the requirement of equipment such as a special lamp and the use of analogical photography or, alternatively, of a Polaroid camera that gives immediate results. A possible answer is to produce stroboscopic digital pictures of motions, using two accessories at the disposal of most teachers and at very low cost: a digital camera, to produce a video of the phenomenon in study and a PC Computer together with a free software, VirtualDub and ImageJ to produce the stroboscopic picture. The data for analysis may be obtained in analogical or digital format, show good quality, as seen in the examples presented