Kater's pendulum
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Kater's pendulum is a reversible pendulum designed and built by Captain Henry Kater in 1817 to measure the acceleration of free fall so that gravity may be calculated without knowledge of the pendulum's centre of gravity and radius of gyration.
The pendulum consists of a rigid bar with a weight near each end. There are also knife edges at each end so that it can be suspended with either end up. A large cylindrical weight is fixed at one end and a small sliding weight near the other. The position of the small weight is adjusted until the period of swing is the same for each knife edge. The period is then that of a simple pendulum whose length is equal to the distance between the knife edges, which allows gravity to be calculated.
Refinements in the method include the use of light wooden weights matched in size, shape, and location (by symmetry) to the nominal masses for balancing aerodynamic effects and the use of electronic timers.
[edit] External articles
- "Mg-2 Kater's reversible pendulum". University of Melbourne, School of Physics, Lecture Demonstration Manual.
- "Kater's pendulum". The Inference Group, Cavendish Laboratory, Cambridge.
- Kater's original work was published in the Philosophical Transactions of the Royal Society in 1818 (Phil. Trans. R. Soc. London, 108, 33, 1818).
