SECOND VERSION
According to Hooke's law, elastic forces are proportional to the spring elongation through a coefficient called the elastic constant k. For a vertical spring-mass system in equilibrium conditions, the mass itself then results proportional to the elongation and to the constant. Therefore by hanging known masses to the spring and measuring the elongation it is easy to evaluate the spring constant.
The idea for the experiment was to measure the spring elongation for three different masses and estimate the spring constant as an average from the three measures.
