The wind was blowing this gatepost chain above Ennerdale. I timed 22 oscillations in 20 seconds so the time period is about 1 second. I was wondering whether being a chain made of links would affect the motion. If it acts like a simple pendulum, then the effective length will be to the centre of mass. As the mass is uniformly distributed, that will be halfway along the chain. There are 14 links of 4cm each so half length is 28cm. Applying the equation T = 2*pi*sqrt(L/g) gives time period of 1.1 seconds. It looks as though the fact that it is a chain has no effect on its pendulum motion.
