<P> The following is not the method Cavendish used, but shows how modern physicists would calculate the results from his experiment . From Hooke's law, the torque on the torsion wire is proportional to the deflection angle θ of the balance . The torque is κθ where κ is the torsion coefficient of the wire . However, the torque can also be written as a product of the attractive forces between the balls and the distance to the suspension wire . Since there are two pairs of balls, each experiencing force F at a distance L / 2 from the axis of the balance, the torque is LF . Equating the two formulas for torque gives the following: </P> <Dl> <Dd> κ θ = L F (\ displaystyle \ kappa \ theta \ = LF \,) </Dd> </Dl> <Dd> κ θ = L F (\ displaystyle \ kappa \ theta \ = LF \,) </Dd> <P> For F, Newton's law of universal gravitation is used to express the attractive force between the large and small balls: </P>

Who gave the first experimental value of g