Pendulum rides are amusement rides based on the motion of a fixed pendulum. Clocks keep time by mechanical resonance in a balance wheel, pendulum, or quartz crystal. This electromagnet releases a gravity lever onto the escapement above the master pendulum. Many clocks keep time by mechanical resonance in a balance wheel, pendulum, or quartz crystal. The angle of oscillation of the pendulum is formula 3. The anchor became the standard escapement used in pendulum clocks. In 1665 Huygens made a curious observation about pendulum clocks. This creates a horizontal "pendulum" with very long oscillation period. This escapement provides the best separation between pendulum and clock mechanism. A familiar example is a playground swing, which acts as a pendulum. The motion of a double pendulum seems chaotic. Arguably the most prevalent example of a stabilized inverted pendulum is a human being. A bike is also an example of an inverted pendulum. The essentials of stabilizing the inverted pendulum can be summarized qualitatively in three steps. Achieving stability of an inverted pendulum has become a common engineering challenge for researchers.