Vibrating string, natural frequencies. Animation showing a number of oscillating strings fixed at both ends, demonstrating different natural frequencies corresponding to an integer number of nodes. The animation shows that the frequency of the vibration increases when the wavelength decreases (more nodes). This model is a numerical simulation that models each string as several thousand elements. Each element is driven by a restoring force proportional to its deflection from the rest position, and an inertial force due to its mass.