Time period of a torsional pendulum

[jackdean29]

For a piece of practical work, I'm investigating which factors alter the time period of a torsional pendulum.

So far, I'm changing the mass of the pendulum, the length of wire, type of wire and thickness of wire, can anyone recommend anything else?

Also, I'm looking at the formula T=2∏√(I/k) where I is the moment of inertia and k is the torsional constant of the wire, but have absolutely no idea where to find the torsional constant of the wire, any ideas?

Thankyou so much! :)

 

[LawrenceC]

I have one anniversary clock that is a pendulum type and runs for a year without winding. It is sensitive to temperature. But that has the effect of lengthening the support wire. The wire that twists in the clock I have is flat, not round.

k = G*J/L
G is the shear modulus.