Pendulum Period Timing

None required — a string and a small, soft weight only.

Disposal: No special disposal — reusable materials.

Materials

• A piece of string about 1m long
• A small weight (a washer, a bag of coins, or similar)
• A stopwatch or phone timer
• Something to hang the string from

Steps

1. Tie the weight to one end of the string and hang the other end from a fixed point.
2. Pull the weight to one side by a small angle (no more than about 15 degrees) and let it go.
3. Time how long 10 full back-and-forth swings take, then divide by 10 to get the period of one swing.
4. Repeat with a shorter string length and compare the periods.
5. Repeat again with a different starting angle (still small) and check whether the period changes much.