A group of students must study the oscillatory motion of a pendulum. One end of a light string is attached to the ceiling, and the other end of the string is attached to a mass hanger so that small disks of various masses may be stacked on the hanger.

Students are provided with data in which an experiment was conducted to determine the relationship between the length of the pendulum and the period of oscillation. The data include a pendulum of length \(0.5\,\text{m}\), for which it took \(81\,\text{s}\) for the pendulum bob to oscillate \(10\) times. However, the experiment was conducted at a location that is not near Earth's surface. The gravitational field strength where the experiment was conducted is most nearly