Computer-Video Method Evaluates Real Motion Data in Real Time for Students

M any mechanics experiments in class or laboratory employ complicated gadgets to collect and represent motion data. These devices include photocells, various types of switch, and "smart" pulleys. Some times these gadgets distract the stu dent's attention away from the behav ior of the moving body, which should be the primary focus of attention. Microcomputer-based methods offer a considerable advantage, and can be used in many experiments. For exam ple, the sonic ranger allows students to record the motion of a body in one dimension. The sonic ranger, smart pulley, and other similar devices have proven successful in teaching kinema tics and dynamics in one dimension. These devices, however, are·normally limited to one dimension. The video camera, on the other hand, is inherently a two-dimensional data-recording device. The difficulty lies in the conversion of information recorded by the video camera into useable, digital information. For this purpose, we devised a computer based system that derives all relevant information from the video signal, and properly processes and displays this information. The name of this system is Orvico (for Object Recording by Video and Computer). This system, and others that were developed inde pendently, were first described sever al years ago. 5 Since then, we have