Hey guys, I've been trying to find out about the expected effect of acceleration and/or motion on a pendulum clock; I asked this question in the mechancial engineering section of PF but didn't get any replies. It pertains to Einsteinian relativity also, specifically the effect of motion on clocks. I understand that a pendulum clock would not be precise enough to measure time dilation, but can we hypothesise an idealised, infinitely precise pendulum clock for the sake of explanation? If a pendulum clock is put on a train and the train accelerates to an inertial speed, will that clock tick at the same rate as a similar clock left behind in the train station (at rest on earth)? If not, does anyone know by how much it would change? Also, if a pendulum clock was built on a train traveling at an inertial speed, such that it didn't undergo acceleration, would it be expected to tick at the same rate as a clock in the train station? Am I right in presuming that a pendulum clock would not work in deep space? Also, if acceleration is the same as gravity, or at least has the same effect, would a pendulum clock accelerating in deep space start to tick, given the correct orientation? Apologies for the glut of questions, it's just something I've been wondering about.