This image (see link below) shoes a Cavendish appartus like the one used to find G. It has a large lead...?

Question

This image (see link below) shoes a Cavendish appartus like the one used to find G. It has a large lead sphere that is 5.9 kg in mass and small one with a mass of 0.047 kg. Their centers are separated by 0.055 m. Find the force of attraction beween them.

*Image link:
http://img227.imageshack.us/my.php?image=scanob6.jpg

Please help me with this problem.
I don't understand the concepts of formulas involved.

Answer 1

Hi. The experiment used a torsion scale, a very thin wire with known strength, to support the center bar. The smaller balls were attracted to the larger ones and caused the wire to twist just a little. From this the mass of the lead balls was used to calculate 'g'.