A set of interactive physics demonstrations, originally written as Java applets in 2004 and re-implemented here in modern HTML5 & JavaScript so they run in any browser.
A driven mass-on-a-spring. Explore resonance by watching the response amplitude and phase lag as you sweep the driving frequency. Adjust the quality factor Q.
Resonance & phase →Two spring-coupled pendulums. See any motion decomposed into its normal modes as a vector in an abstract state space, and watch the resulting beats.
Normal modes & beats →N beads on a stretched string. Discover how only N standing-wave modes exist, and how higher mode numbers alias back onto the fundamentals.
Standing waves & aliasing →