Simple Harmonic Motion Calculator
Where an oscillator is and how fast it moves, at any instant.
The universal oscillation
x = A sin(ωt + φ), ω = 2πf
Pendulums at small angles, masses on springs, a guitar string's fundamental, voltage in an AC outlet: all the same equation. Peak speed is Aω at the center; peak acceleration Aω² at the extremes, which is why speaker cones and engine valves are limited by frequency squared, not frequency.