Re: An equation for a Bifilar pendulum's period

The period of a Bifilar pendulum (in the plane defined by the two parallel strings) is 
the same equation as the period of a regular pendulum:  T=2pi (L/g)^1/2.  The 
interesting thing is that the length L can now be measured very precisely, because 
when you work out the details, L turns out to be exactly the length of the string, from 
support point to where it's attached to the swinging object (assuming both strings 
are the same length).  For a regular (1-string) pendulum, the length needs to be 
measured to the center of mass of the swinging object, which is often difficult to 
measure accurately.  Because of this, measuring the period of a Bifilar pendulum is 
one of the easiest ways to accurately measure g.