Procedure: a) Attach a small bob to the thread and b) Measure the length of the thread, L by a ruler; starting with 120.0 cm. Displace the bob of the pendulum by a small angle ~ 4 degrees and release. c) Record the time for 20 complete oscillations, t using the stop watch. Calculate the period of oscillation by using, T = t / 20 d) Repeat the experiment using different lengths such as 120.0 cm, ... 60.0 cm