Pendulum clock

A pendulum clock uses a swinging weight called a pendulum to keep time. The pendulum swings back and forth at a regular interval, determined by its length and gravity. This consistent motion controls an internal mechanism that moves the clock’s hands at a steady pace. A weights or spring provides energy to keep the pendulum swinging, compensating for energy lost through friction. Because the period of a pendulum's swing is very predictable, this design allows the clock to measure time accurately over long periods. Pendulum clocks were a major advancement in precise timekeeping before the advent of modern electronic clocks.