Nudge something away from where it was at rest, and often it will push back. And then overshoot. From atoms to bridges to wheeled luggage, much of the world is in simple harmonic motion Yesterday my ...

Grease both lubricates and keeps contaminants out of bearings. But its job is often made difficult by back-and-forth, or oscillatory, motion. Printing presses are a classic example: Frequent returns ...