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Coupled Global Kater's Pendulum

Supported by Physics DepartmentMississippi State University
Fig.1. A Schematic diagram of Kater's Pendulum
(a) opposing knife edge pivots from which pendulum is suspended
(b) fine adjustment weight moved by adjusting screw
(c) coarse adjustment weight clamped to rod by setscrew
(d) bob
(e) pointers for reading

A Kater’s pendulum is a commonly available setup. Measuring the local gravitational acceleration (‘g’) using Kater’s pendulum is a common undergraduate experiment. Gaining about 5 to 6 significant figures on the value of ‘g’ is not difficult. This can be further improved if an error co-related pair of pendulums is used. Further, if the pendulums are placed on opposite sides of the Earth, one could also distinguish the extra-terrestrial sources of variation of ‘g’.

One source of extra-terrestrial source of variation of ‘g’ is revolving moon. So we setup 2 pendulums on the opposite sides of the Earth. This was just a curious experiment we wanted to try out and try to push the boundaries of the value of ‘g’ that can be obtained by the Kater’s pendulum. In collaboration with VTU-CMR Institute of Technology where the other pendulum is placed, we hope to have enough data by mid – 2013.