A spherical pendulum is similar to a simple plane pendulum, except that the pendulum is not constrained to move in a plane; the mass m is free to move in two dimensions along the surface of a sphe...A spherical pendulum is similar to a simple plane pendulum, except that the pendulum is not constrained to move in a plane; the mass m is free to move in two dimensions along the surface of a sphere. The room was then darkened, the flashlight turned on, and the flashlight pendulum allowed to swing back and forth for several minutes above a camera which was on the floor pointing up toward the ceiling.