Try the New Resonance Sim!
Try the new Resonance Sim for advanced undergraduate students. Observe resonance in a collection of driven, damped harmonic oscillators. Vary the driving frequency and amplitude, the damping constant, and the mass and spring constant of each resonator. Notice the long-lived transients when damping is small, and observe the phase change for resonators above and below resonance.
I really love this one! Collision sim was my favorite, now this one!