On Fig. 2.1, measure the pendulum length $l$ in centimetres, reading to the nearest millimetre.
Fig. 2.1 is a one-eighth scale drawing. $L$ represents the pendulum's true length. Calculate $L$.
The student pulls the bob through a small angle and lets it go so that it moves to and fro. Fig. 2.2 illustrates one full oscillation of the pendulum.
State the time $t$ for 20 oscillations shown in Fig. 2.3.
The student times 20 oscillations two more times, obtaining $21.30\,\text{s}$ and $21.28\,\text{s}$. Find the average time $t_{av}$ for 20 pendulum oscillations.
The period $T$ is the duration of one full pendulum oscillation. Calculate $T$.
Calculate $g$, the acceleration of free-fall, using the equation provided: $g = \frac{11.1}{T^2}$. Give your answer to 3 significant figures.
To determine the pendulum period $T$, the student first finds the average time for 20 oscillations. Suggest why the student did not opt to measure the average time for 2 oscillations.
Suggest why the student did not choose to measure the average time for 200 oscillations.