Hacker News Reader

The whole article appears use a very loose philosophical definition of "impedance". As a mechanical engineer, none of the mechanical examples are correct either when there are real-world examples that actually meet the more strict technical definition of impedance matching, mass-damper systems in skyscrapers is immediate example that comes to mind.

View on HN

Mass damper systems were really important in cars too before we had deep simulations of structures. Putting some loosely coupled weight in some spot to keep the whole thing from vibrating was a breakthrough.

Is gearing up or down, with a fixed power budget, a valid example in the strict sense? Genuinely asking.

That's a pretty decent example IMO.

No. A gear train is just a transfer of force/torque. It's analogous to a simple lever for rotational motion. Mechanical impedance is almost always referring to harmonic forces (think of spring systems and structural dynamics). Impedance in fluids also fall under mechanical impedance but it's usually classified separately as acoustic impedance.

I think what they're getting at, and is valid, is how the speed/torque relationship is similar to voltage/amperage. There's nuance which can separate those ideas.

Reply on news.ycombinator.com