Doing One Thing, Well: The UNIX Philosophy

The Unix operating system has been around for decades, and it and its lookalikes (mainly Linux) are a critical part of the computing world. Apple’s operating system, macOS, is Unix-based, as are Solaris and BSD. Even if you’ve never directly used one of these operating systems, at least two-thirds of all websites are served by Unix or Unix-like software. And, if you’ve ever picked up a smart phone, chances are it was running either a Unix variant or the Linux-driven Android. The core reason that Unix has been so ubiquitous isn’t its accessibility, or cost, or user interface design, although these things helped. The root cause of its success is its design philosophy.

Good design is crucial for success. Whether that’s good design of a piece of software, infrastructure like a railroad or power grid, or even something relatively simple like a flag, without good design your project is essentially doomed. Although you might be able to build a workable one-off electronics project that’s a rat’s nest of wires, or a prototype of something that gets the job done but isn’t user-friendly or scalable, for a large-scale project a set of good design principles from the start is key.

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Trebucheting Tennis Balls At 124 MPH

A trebuchet is one of the older machines of war. It’s basically a sling on a frame, with a weight that you can lift up high and which pulls the sling arm over on release. Making one opens up the doors to backyard mayhem, but optimizing one opens up the wonders of physics.

[Tom Stanton] covers just about everything you need to know about trebuchet building in his four-part video series. Indeed, he sums it up in video two: you’ve got some potential energy in the weight, and you want to transfer as much of that as possible to the ball. This implies that the optimal path for the weight would be straight down, but then there’s the axle in the way.  The rest, as they say, is mechanical engineering.

Video three was the most interesting for us. [Tom] already had some strange arm design that intends to get the weight partially around the axle, but he’s still getting low efficiencies, so he builds a trebuchet on wheels — the classic solution. Along the way, he takes a ton of measurements with Physlets Tracker, which does video analysis to extract physical measurements. That tip alone is worth the price of admission, but when the ball tops out at 124 mph, you gotta cheer.

In video four, [Tom] plays around with the weight of the projectile and discovers that he’s putting spin on his tennis ball, making it curve in flight. Who knew?

Anyway, all four videos are embedded below. You can probably skip video one if you already know what a trebuchet is, or aren’t interested in [Tom] learning that paying extra money for a good CNC mill bit is worth it. Video two and three are must-watch trebucheting.

We’re a sad to report that we couldn’t find any good trebuchet links on Hackaday to dish up. You’re going to have to settle for a decade-old catapult post or this sweet beer-pong-playing robotic arm. You can help. Submit your trebuchet tips.

Thanks [DC] for this one!

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120 Second Shower Cap

Do you have a couple of minutes? Literally and precisely, two minutes. That’s how long these ten songs play. So what? A short song is not new, but these ten songs are part of a campaign to encourage residents of Cape Town, South Africa to cap their showers at one-hundred-twenty seconds. Some of us do not have to worry about droughts or water bills, but most of us are concerned about one or both of those, and this ingenious campaign alerted people to the problem, gave them the means to time themselves, and made it pleasant, not oppressive. The songs are freely available, and one might even pique your listening tastes from the biggest stars in South Africa.

So, where is the hack? Some of us have experimented with egg timers on the towel rack, timers on the showerhead, servos on the faucet knobs, or occupancy sensors, but those are strong-arm techniques or only for measuring, not regulating water use. These songs attack the most viable vector, the showerer. Or is it showeree? Telling people there is a drought is one thing, but giving them the ability to regulate themselves in such a way that they comply is a hacker’s approach. The songs on the site do not autoplay so there will be no hanging out under the water spray to find the best song. Which is your favorite?