本田, 敦也

Honda, Atsuya

high-speed video camera

画像処理プログラミング

image processing programming

OpenCV

物理実験

physics experiment

力学的エネルギーの保存

mechanical-energy conservation law

Recently, the chance to use commercially supplied high-speed video cameras has been increased in physics education to confirm kinetic laws of the motion of bodies. The data files of movies are generally so large in capacity that there are the technical issues to store, transfer, and display the data. In consequence, the resolution of the movie is not enough to determine the position of moving bodies precisely. In addition, the high-speed movies consist of a large number of frames, so that we need to be computer-assisted and to use high-efficient Computer-Vision (shortly, CV) software of the image processing. Thus in order to assert the mechanical-energy conservation law in demonstrational experiments, we recorded motion of some pendulums in the videos with 512x384 pixels in resolution and 300 frames per second in frame rate, and obtained the position of the bodies with a handmade software using OpenCV libraries. In a case of a pendulum, of which the body has the size of 81 pixel in diameter on the image and sweeps in an arc with the horizontal amplitude of ±58 pixels and with the quite small vertical range of 1.1 pixel, the time-dependence of kinetic and potential energies showed the expected compensating behaviors with acceptable errors from the results with the reading positional accuracy of about 0.03 pixel.