3 ms·

I don't think that's quite right - friction obviously causes the pendulum swing to slow down, but even as it slows the frequency of the swing remains constant (

I don't think that's quite right - friction obviously causes the pendulum swing to slow down, but even as it slows the frequency of the swing remains constant (because the amplitude changes to compensate for the slowed swing) So until the swing actually stops due to friction, the pendulum will continue to keep time. There are of course exceptions, for example if the friction is actually changing (due to air pressure / humidity changes) the clock will go out of sync. This is observable in real life pendulum clocks and I didn't think it was an area of debate - am I missing something here?

krastanov 11y ago
Actually friction changes the frequency, see [1]. Moreover there is this general idea in spectroscopy (whether of atoms or of pendulum clocks) that to precisely measure a frequency you need the smallest dissipation possible (check wikipedia about linewidth-lifetime relations, Q-factors, etc). Basically the precision with which you can measure a frequency is 1/lifetime_of_the_phenomenon. Higher dissipation means lower precision. See [1] https://en.wikipedia.org/wiki/Harmonic_oscillator#Damped_harmonic_oscillator https://en.wikipedia.org/wiki/Harmonic_oscillator#Damped_har... edit: If this change of frequency is calibrated it is not an issue, but this calibration is not trivial and friction is something a lot less stable than the other physical properties that govern the clock.