Why does a torsion balance oscillate during the Cavendish experiment?

Question

Is it the tension in the suspending wire?

Answer 1

The oscillation is due to the torsional moment of the support wire. The wire is a torsion spring. The assembly is a damped harmonic oscillator, with air friction causing the damping. Moving the lead balls shifts the center of oscillation, and the spring constant is found from the oscillation period, mass, and arm length. Don't forget to correct the oscillation frequency for damping.

Answer 2

The tension has nothing to do with the oscillation.

The oscillation is caused by the gravitational attraction of the masses at the ends of the balance arm. The tension wire supporting the whole mess is made so thin that, for small deflections, it has essentially no resistance to the movement caused by the masses, so the motion as measured by the reflecting mirror is due only to the attractive nature of the masses and can therefore be used to fairly accurately measure G, the universal gravitational constant.

Answer 3

Yes

Answer 4

http://www.phys.uconn.edu/~hamilton/phys258/N/cav.pdf#search='torsion%20balance%20oscillate%20during%20the%20Cavendish%20experiment'