PENDULUM

[noun] [C] - a device consisting of a weight on a stick or thread which moves from one side to the other, esp. one which forms a part of some types of clocks, or (figurative) a change esp. from one opinion to an opposite oneThe pendulum in the grandfather clock swung back and forth. He made pendulums of string and small weights and established the relationship between length of string and time of swing.The spaceship's jets were fired periodically to dampen a side-to-side pendulum motion that had developed.(figurative) As so often in education, the pendulum has swung back to the other extreme and testing is popular again.(figurative) The pendulum of society's concern will swing again toward caring.See picture: Clocks and watches