How is the pendulum understood in Buddhism?
The only thing I heard about pendulum in Buddhism was a metaphor used by my first teacher. He said, in the past people used to fluctuate, like a pendulum, between being extremely spiritual in one life and extremely materialistic in another life. He said, in ancient times the pendulum swung a lot slower, maybe over the course of 50 lives. But in our times, the pendulum is so fast that it is effectively in a quantum state - in both extremes at the same time. This is why, he said, now it is appropriate and even desirable to be both spiritual and successful in the world.

Never heard of any other mention of pendulum in any Buddhist context.