Simple pendulum

Procedure

1. Secure the string to the clamp. Measure from the pivot to the bob’s centre.
2. Move the bob through an angle smaller than about 10° and let go without a push.
3. Time 20 full oscillations. Count one whenever the bob returns to the same position moving in the same direction.
4. Repeat the timing and average the total times. Divide that mean by 20 to find T.
5. Collect readings at several lengths. Plot T² against L, find the slope, and calculate g = 4π²/slope.

Precautions

1. Check that the stand is steady and leave the swing path clear of people and objects.
2. Keep the angle small. Repeat timings to reduce the effect of reaction-time error.