In this experiment we measure Earth’s gravitational acceleration g by a different method: free fall of a ball. Knowing the drop height and measuring the fall time, we obtain g from g = 2h/t². The key difference from the pendulum experiment: here the main error comes from your reaction time — and its effect on g is doubled.
Compare with the pendulum experiment
If you’ve done both experiments, compare the g values and the error bars from each. Which method was more accurate? After the reveal, was the “true” value inside the error bar of both methods? This is the classic exercise of the scientific method: one quantity, two independent methods, cross-check.