Halliday, Resnick & Walker — Motion Along a Straight Line: Problem 86

Measuring the free-fall acceleration. At the National Physical Laboratory in England, a measurement of the free-fall acceleration \(g\) was made by throwing a glass ball straight up in an evacuated tube and letting it return. Let \(\Delta T_L\) in Fig. 2.31 be the time interval between the two passes of the ball across a certain lower level, \(\Delta T_U\) the time interval between the two passages across an upper level, and \(H\) the distance between the two levels. What is \(g\) in terms of those quantities?