Resonance is universal constructive addition of force-driven velocity

Evidence

Resonance for an oscillator corresponds to alignment (in-phase condition) of force and velocity. But force causes acceleration, which increases the velocity, so resonance corresponds to constructive addition of velocity to preexisting velocity. This applies universally, to a single oscillator, a complex structure such as a string, a membrane, a plate, a solid, and even to air. — Eric J. Heller, Why You Hear What You Hear- An…, 1012

Categorization

• DEFINE: Redefines resonance from the familiar ‘in-phase force and velocity’ description into a causal mechanism: velocity-building through constructive addition, universal across all vibrating systems.
• corroborated: 2 independent passages support this claim — Eric J. Heller, Why You Hear What You Hear- An…, 1012
• XREF: connects to: Force and acceleration are in phase yet work requires force and velocity in phase; String vibration is driven by changing force direction, not changing tension — Eric J. Heller, Why You Hear What You Hear- An…, 772; Resonance requires confined old amplitude returning in phase with fresh drive amplitude (+7 more)

Broader Connections

• Impedance equals applied force divided by attained velocity #expands (0.78)
• Adding damping to a resonance paradoxically makes it more audible by widening its bandwidth #complicates (0.75)
• Spatial-averaged measurement curves reveal real resonances through shared bumps. #expands (0.72)