According to Einstein's equivalence principle, the inertial mass and the gravitational mass are identical. In this study, we charried out an experiment on the harmonic motion of a spring that moved horizontally in one dimension without friction. Objects suspended at both ends of two springs are set to perform a harmonic motion perpendicular to the direction of gravity. The analysis for measuring the inertial mass of an object by using the spring force without the effect of gravity was discussed, and the inertial mass was estimated by comparison with the gravitational mass obtained by using the measurements of the spring constant, frequency, period, etc.

Keywords: 2015 Science revision curriculum, Equivalence principle, Inertial mass, Harmonic motion, Gravitational mass, One-dimensional motion