Editing Theory (section)

== The Device == 
Kater’s pendulum is a physical pendulum composed of a metal rod with two knife edge pivots towards each end of the rod. The exact location of the knife edges, relative to the ends of the rod, is not of extreme importance, as long as they are relatively symmetrical. However, the distance between the knife edges must be measured precisely* enough to achieve the level of accuracy desired in the experiment. There is a weight attached to each end of the pendulum. These two masses are of different weights. This is done intentionally and is the reason Kater's Pendulum works. The pendulum can be suspended by the knife edges and set to swinging by resting either knife edge on a flat, level surface in the small mass down (SMD) and small mass up (SMU) orientations. The "large" weight is attached at a fixed position and the small weight is adjustable. This adjustment allows the pendulum's period to be adjusted. As an improvement to the pendulum design, a thin "needle" has been attached to each end of the pendulum. As the period must be measured very precisely (see [[Uncertainties]]), these "needles" allow for a smaller angle of oscillation while still allowing the pendulum to pass through a photogate.