In this experiment we determine a spring’s constant k by hanging different weights and measuring the extension. Unlike the previous two experiments (pendulum and free-fall), here a single measurement is not enough — you collect several points and perform a linear fit. This technique also exposes the ruler’s systematic zero-point offset.
Why this experiment is different
In the “Python analysis” section we fit F = k·x + b. If b is zero, the ruler is calibrated. If it’s nonzero, the value of b tells us exactly how large the ruler’s zero-point offset is. This idea — using the structure of the model to identify systematic error — is one of the most important laboratory skills.