HOME PHYSICS EXPERIMENT OF MEASURING EARTH RADIUS BASED ON SMARTPHONE

This paper designs three methods of the earth's radius measurement, the sunset time difference method, the sun elevation difference method and GPS positioning method, which is in the context of COVID-19 outbreak and based on the smart phone. These experimental methods provided in this paper don't need professional physics experiment measuring tool and can be completed at home. The earth radius measured by the sunset time difference method and the sun elevation method are 6246km and 6239km with the measuring relative errors 2.0% and 2.1%, respectively. In the GPS positioning method, three point taking methods are designed including the point taking at the same longitude, at the same latitude and any point. The measured earth radius are 6432km, 6400km and 6343km respectively, and the measuring relative error can reach 1.0%, 0.5% and 0.4% respectively. The error accuracy of all methods in this paper can meet the requirements of basic physics experiment course design, and the measurement accuracy of GPS positioning method is obviously better than sunset time difference method and solar elevation method. At the same time, the main influencing factors of measurement error are also analyzed.