Simple Setup Answers Complex Question On The Physics Of Solids

February 1, 2022 by Dan Maloney 17 Comments

Thought experiments can be extremely powerful; after all, pretty much everything that [Einstein] came up with was based on thought experiments. But when a thought experiment turns into a real experiment, that’s when things can get really interesting, and where unexpected insights crop up.

Take [AlphaPhoenix]’s simple question: “Are solid objects really solid?” On the face of it, this seems like a silly and trivial question, but the thought experiment he presents reveals more. He posits that pushing on one end of a solid metal rod a meter or so in length will result in motion at the other end of the rod pretty much instantly. But what if we scale that rod up considerably — say, to one light-second in length. Is a displacement at one end of the rob instantly apparent at the other end? It’s a bit of a mind-boggler.

To answer the question, [AlphaPhoneix] set up a simple experiment with the aforementioned steel rod — the shorter one, of course. The test setup was pretty clever: a piezoelectric sensor at one end of the bar, and a hammer wired to a battery at the other end, to sense when the hammer made contact with the bar. Both sensors were connected to an oscilloscope to set up to capture the pulses and measure the time. It turned out that the test setup was quite a challenge to get right, and troubleshooting the rig took him down a rabbit hole that was just as interesting as answering the original question. We won’t spoil the ending, but suffice it to say we were pleased that our first instinct turned out to be correct, even if for the wrong reasons.

If you haven’t checked out [AlphaPhoenix] yet, you really should. With a doctorate in material science, he’s got an interesting outlook on things, like calculating pi using raindrops or keeping the “ultra” in ultra-high vacuum. Continue reading “Simple Setup Answers Complex Question On The Physics Of Solids” →

How Do Capacitors Work?

January 6, 2022 by Al Williams 6 Comments

If you are like [The Science Asylum], you might wonder how a capacitor can work since, at their core, they are nothing more than a gap filled with air or another insulator. He explains how in a recent video you can see below.

Of course, at DC, a capacitor doesn’t conduct any better than the insulator used as its dielectric. However, a DC voltage has to start sometime and when it does, it briefly looks like AC. The video explains it all in simple terms. Of course, if you are math savvy, you can probably get as much out of the normal C=dQ/dV equation.

If that doesn’t speak to you, the explanation in the video about charges will shed some light. He even shows an animation of the classic “hydraulic model”, which is helpful to develop intuition about the process.

Continue reading “How Do Capacitors Work?” →

Attack Of The Eighty-Foot String Shooter

January 1, 2022 by Brian McEvoy 24 Comments

String shooters are exciting because they adhere to the laws of physics in that peculiar way that makes us ask, “How?” and “Why?” After a bit of poking and prodding, maybe some light rope burn, we probably have a few ideas on how we’d make our own. [Nick Belsten] and [Joey Rain] saw some desktop models and thought, “Let’s make that puppy eighty feet long!” Video also embedded after the break.

Instead of hobby motors, flashlight batteries, and toy car wheels, they choose a washing machine motor and bike tires, then plug into an extension cord. The three-minute video isn’t a how-to build because once you start welding this kind of hardware together, you are already flying by the seat of your pants. You will see a front yard with people delighting in the absurdity of launching rope continuously over the treetops. There’s plenty of room for observing a wave traveling along the cord or polishing your fingernails in a hurry.

We want to make string shooters for the office and add our personal flavor, like lights or colored string so they’re safe to touch. If you have a unique twist on any physics experiments, drop us a line, but for insurance reasons, we’ll add that you should not make a chainsaw without a guide bar, aka, the forbidden chain-saber.

Continue reading “Attack Of The Eighty-Foot String Shooter” →

LED Matrix Hourglass Knows Which Way Is Up

October 8, 2021 by Donald Papp 6 Comments

[Fearless Night]’s slick dual hourglass doesn’t just simulate sand with LEDs, it also emulates the effects of gravity on those simulated particles and offers a few different mode options.

The unit uses an Arduino (with ATMEGA328P) and an MPU-6050 accelerometer breakout board to sense orientation and movement, and the rest is just a matter of software. Both the Arduino and the MPU-6050 board are readily available and not particularly expensive, and the LED matrix displays are just 8×8 arrays of red/green LEDs, each driven by a HT16K33 LED controller IC.

The enclosure and stand are both 3D-printed, and a PCB not only mounts the components but also serves as a top cover, with the silkscreen layer of the PCB making for some handy labels. It’s a clever way to make the PCB pull double-duty, which is a technique [Fearless Night] also used on their earlier optical theremin design.

Those looking to make one of their own will find all the design files and source code handily available from the project page. It might not be able to tell time in the classical sense, but seeing the hourglass displays react to the device’s orientation is a really neat effect.

Game Development Hack Chat

August 16, 2021 by Dan Maloney No comments

Join us on Wednesday, August 18 at noon Pacific for the Game Development Hack Chat with Kyle Donnelly!

Chances are we all have fallen into the time trap of computer games at one point or another. It’s easy to do — the worlds that games put before us can be immersive and addictive, and even if they’re populated by fantastical creatures hell-bent on our virtual destruction, they offer a degree of escapism and relaxation that can be hard to come by with any other form of entertainment.

But what does it take to build these virtual worlds? How exactly does one come up with all the ideas needed to make a game fresh and exciting? And once you’ve got the ideas, how do you turn them into the code needed to make the whole thing work? Kyle Donnelly has quite a bit of experience with the game development process, seeing his idea through from initial prototyping to working with a publisher and even getting the game demonstrated at conventions. Along the way, he picked up a collection of tips and shortcuts to make the process easier, as well as developing a small suite of tools to help set up and test game levels quickly and easily, and to deal with the custom physics of his virtual world.

Join us as Kyle stops by the Hack Chat to talk about game development from an angle that rarely gets much coverage — from the software side.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, August 18 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Banner Art: Video Games Awesome Fanart by sacolin99.

Improving OLED VU Meters With A Little Physics

August 9, 2021 by Tom Nardi 23 Comments

Last month we featured a project that aimed to recreate the iconic mechanical VU meter with an Arduino and a common OLED display. It was cheap and easy to implement, and promised to bring a little retro style to your otherwise thoroughly modern project.

[sjm4306] liked the idea, but thought it was a tad too stiff. So he’s been experimenting with adding some physics to the meter’s virtual needle to better approximate the distinctive lag and overshoot that’s part and parcel of analog indicators. Obviously it’s something that can only be appreciated in motion, so check out the video below for an up-close look at his quasi-retro indicator.

Unfortunately there’s no code for you to play with right now, but [sjm4306] says he’ll release it on the project’s Hackaday.IO page once he’s cleaned things up a bit. We know it will take more than a few wiggling pixels to pry real analog indicators out of some hacker’s tool boxes, but anything that helps improve the digital approximation of this sort of vintage hardware is a win in our book. Continue reading “Improving OLED VU Meters With A Little Physics” →

3D Printing May Disprove Lord Kelvin

August 3, 2021 by Al Williams 28 Comments

If you think 3D printing is only good for benchies, key chains, and printer parts, you might enjoy the paper by two physicists from Wesleyan University and the University of Gothenburg. Lord Kelvin — also known as William Thomson — hypothesized a shape known as an isotropic helicoid. As its name implies, the shape would look the same from any angle. Kelvin predicted that such a shape would spin as it sank in a liquid. Turns out, 3D printing proves it wrong. (The actual paywalled paper is available.)

It might seem strange that scientists are only now getting around to disproving a 150-year old hypothesis. However, the paper’s authors think Kelvin may have built the structures — he provided precise instructions — and simply dropped it when it proved incorrect.

Continue reading “3D Printing May Disprove Lord Kelvin” →