© Blayne Heckel.
The torsion pendulum shown here was used at the University of Washington to compare the gravitational acceleration of 4 titanium (Ti) test bodies to that of 4 beryllium (Be) test bodies. The photograph shows the gold-coated pendulum lifted off a support plate that is held by the vertical posts. The pendulum's gold coating is a good conductor of electricity, and prevents a charge from building up on the pendulum that would cause electrostatic interactions to hide a gravitational signal. (Unit: 3)