Comment on “An accurate determination of the acceleration of gravity for lecture hall demonstration” [Am. J. Phys. 55, 324–330 (1987)]

The effect of air resistance on a falling object is well known and forms the basis of many undergraduate physics experiments and demonstrations. Rueckner and Titcomb¹ described an accurate version of the experiment in this journal in 1987, concluding that the drag coefficient for a baseball was 0.270 ± 0.005. In a similar experiment conducted recently,² it was found that the drag coefficient for a low speed baseball is 0.62 ± 0.05, despite the fact that the fall heights and times were very similar in the two experiments. The origin of the discrepancy can be traced to two different estimates of the average acceleration used by the first authors. Rueckner and Titcomb measured an accurate fall time t over a distance H of slightly less than 6 m and obtained an average (constant) acceleration g₁ = 9.615 m/s² for the baseball using the formula $H=...$