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Old 8th Feb 2009, 18:19
  #51 (permalink)  
Join Date: Aug 2006
Location: Bedford, UK
Age: 40
Posts: 313
Mixture. Given a decent set of tables, the sky is a remarkably accurate way of determining local time.

And yes, the "pivot" bit was a typo. I still reckon a good jewelled bearing would give you about the minimum possible loss of energy at the hanging point.

Rjm, the gravity, or indeed the magnetism, without some other kind of force to remove the energy from the system, will not cause the system to slow down. All of the energy that the pendulum has at the top of the swing, in the form of potential energy, is transferred to kinetic energy by the bottom of the swing. As the pendulum rises again, the energy is transferred back into potential energy. The total energy is "conserved" unless there is some kind of friction or other method of removing energy from the system.
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