The first precise pendulum clock imported into North America failed to keep accurate time. How much does the local variation in effective g affect time keeping?

Answer: We typically teach our students to use g = 9.8 or 9.81 m/s2. (I prefer to use 10 m/s2 since it is far easier to calculate with and most problems do not need 2% precision.) However, g varies. The first high-tech pendulum clock imported into North America was carefully calibrated in Holland to within a few seconds per day, but failed to keep accurate time in the colonies. When returned to Holland for service, it kept accurate time again, indicating that the clock itself worked properly. How much does the local variation in g affect time keeping?

We can either estimate the variation in g due to various causes, or just estimate it directly. Let’s try both. The fact that...

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