A system with N independent vibrating parts has N distinct normal modes

Evidence

For two beads, we have two modes of vibration, instead of one. This leads us to suspect there will be N different modes for N beads. A pure mode is identified as an oscillation in which the parts of the object (beads in this case) moved sinusoidally with a single frequency. — Eric J. Heller, Why You Hear What You Hear- An…, 788

Categorization

• DEFINE: Defines ‘pure mode’ as a single-frequency sinusoidal oscillation of all parts.