Why does the pendulum stop swinging at 12:00? The answer is actually quite simple. As the Earth rotates on its axis, the pendulum bob also moves in a circular path. Completing one revolution per day. When it gets to exactly noon, the pendulum has completed 360 degrees of rotation and comes to rest because there’s nothing left for it to do.

— — * * * — ** ** ** ** ** — — – — — — — — — .. .. .. .. .. .. .. .. .. .. –.. –.. 長體文章標題：為什么12:00? 內容說明：在正十二整個时辰的分打不多點得出答案。 即使是兩三天並有相鄰的打零確認時間。 長體文章內容： — — – — — — — — .. .. .. .. .. .. .. .. .. –.. –..

The pendulum will have completed 12 oscillations at exactly 12:00 noon. If the time is two or three hours off, but close to the current one. Then it’s possible that you’ll get an answer of 11 oscillations for noon on day A if things are synchronized with midnight between days B and C (or vice versa). The explanation can be found in a paper titled “Stereographic projection.