Cavendish Experiment Article Index for
Cavendish
Limousines in
Cavendish
Website Links For
Cavendish
 

Information About

Cavendish Experiment




The apparatus comprised a six-foot (1.8 m) wooden rod with metal spheres attached to each end, suspended from a wire. Two 350 pound (159 kg) lead spheres placed nearby exerted just enough Gravitational Force to tug at the end-weights, causing the wire to twist.

To prevent air currents from interfering, Cavendish set up the apparatus in a wind-proof room and measured the twist (torsion) of the wire using a Telescope .

From the twisting force in the wire and the known masses of the spheres, Cavendish was able to calculate the value of the gravitational constant. Since the force of the gravitational attraction of the earth for an object of known mass could be measured directly, the measurement of the gravitational constant allowed the mass of the earth to be calculated for the first time. This in turn allowed the calculation of the masses of the sun, the moon, and the other planets.

Modern measurements of the gravitational constant still use variations of this method.

A description of Cavendish's experiment and a summary of several similar experiments are given by the 1911 ''Encyclopædia Britannica''.


REFERENCES


  • Cavendish, H. "Experiments to determine the Density of the Earth", ''Philosophical Transactions of the Royal Society of London'', (part II) 88 p.469-526 (1798)

  • "Gravitation". ''Encyclopædia Britannica'', 1911.

  • B. E. Clotfelter. "The Cavendish experiment as Cavendish knew it." ''American Journal of Physics'', 55:210 (1987).



EXTERNAL LINKS