A simple pendulum is a mass (bob) attached to a string or rod of fixed length that is free to swing back and forth. When the pendulum is displaced from its equilibrium position and released, it will oscillate back and forth in a regular pattern known as simple harmonic motion (SHM).
The motion of the pendulum is characterized by a constant period, meaning it takes the same amount of time for the pendulum to complete one full swing regardless of the amplitude of the swing. The motion is also sinusoidal, with the displacement of the pendulum following a sine or cosine function.
The frequency of the pendulum's oscillation is determined by the length of the string or rod and the acceleration due to gravity. A longer pendulum will have a longer period and lower frequency, while a shorter pendulum will have a shorter period and higher frequency.
Overall, the simple pendulum is a classic example of a system that exhibits simple harmonic motion, with its motion governed by the restoring force provided by gravity as it swings back and forth.