It helps to know what a Newtonian fluid is before you start thinking about non-Newtonian fluids. Conveniently, just about every fluid you can think of is Newtonian. When you push on a fluid, it moves out of the way. Some move fast, some move slow (this is quantified as viscosity), but when a fluid seizes up and stops,,when it becomes like a solid in response… That goes against Newton!
Perhaps the most common non Newtonian fluid people run across [foreshadowing] is cornstarch and water. It’s used to thicken gravy and other sauces (because of viscosity). But when making gravy, you are cautioned to mix the corn starch in cold water first and then add that to your hot liquid that needs to be thickened to avoid clumps. This is because the corn starch on the outside will mix with water first and be agitated (pressed on) by the hot liquid and turn solid, preventing even distribution of the inner cornstarch. But if you mix it with child water first all of the corn starch will be able to mix with the hot water.
So we mixed it 50lbs bag of corn starch with water, and learned that if you put water into cornstarch it will mix on the surface, and further attempts to mix in more water will cause the outer cornstarch solution to turn solid. Preventing further mixing…. Much like cornstarch dumped directly into hot water. The right way to mix large batches is to add the corn starch slowly into water until the desired thickness is achieved.
You can then put that on a speaker and play a time of just the right frequency to see the corn starch turn solid, be thrown in the air and turn liquid again on the way down
Or you can jump in a big tub of it and see if you can start running before you begin to sink. It’s harder than it looks.
Or you can cut to the chase and just build a trough that you can run across… Or stop and sink into.
Making liquid dance on a speaker is pretty cool, and visually memorizing, but hands on (or feet in) is really the best way to experience and believe in the properties of Non Newtonian fluids.
No matter what you do though, make sure you leave lots of time for cleanup.
We travelled to Clemson for the total solar eclipse. We threw a few simple, random building materials I the car as we we’re heading out. And when we got there we had a little bit of time… So we made a cereal box viewer, sans the cereal box… And way better. Josh gave lots of demos and explained how it worked and some of the more interesting properties. So much so that we were interviewed for and included in a book!
One of the neat things about the book was that Marie Harris, one of our favorite librarians from “The Loft” (a cool teen only space at Imaginon – the Children’s Library) in Charlotte – send me an email after she read the book. We’re quoted talking about Baily’s Beads which was truly the most amazing thing that I got to see being in totality.
After seeing a small artistic tree made with polished stones, I was inspired to create one with LED as a nightlight for my daughter. The trunk and branches are made with enameled (magnet) wire. The LEDs are automatic rotating RGB so they change colors over time. The first tree used “fast blink” LEDs which change color about once per second, which looking back at it (and when looking directly at it) was somewhat seizure inducing. Later refinements used “slow blink” RGB LEDs that slowly changed from one color to the next over about 5-10 seconds. Interestingly, when powered on, all the LEDs go through the same color shift pattern, but fairly quickly small differences in timing cause the LEDs to be all different colors at all different places in the sequence. It’s quite soothing and almost difficult to tell that they are changing at all.
The hardest part of this project is tinning the magnet wire. Each end of the wire must be stripped of the enamel coating and soldered before (easier) or after (harder) twisting the trunk/branches together. Using two different colors of enameled wire make it easy to discern the positive and negative leads to solder to the LEDs.
The Tree was powered by a 5V 0.5A USB power block for charging cell phones – we called them marshmallows. The real trick there was cutting the USB cord and attaching the tiny little wires to the base of the tree.
In spite of may people wanted a tree, few people made them due to the time involved. But it was a great “learn to solder” project because of so many solder joints required, the low quality required, and the fast feedback loop. We soldered this kit “hot” – the power was connected the whole time you were soldering, so you knew if it was working or if you made a mistake right away. That’s a much better way to learn to solder.
With all that potential Ben and Mike create a much smaller scale kit that was immediately popular. The tree could be built in a single visit to the Makerspace and enjoyed at home that very night. The problem was that it to a lot of prep work to build a kit! The tinning was a pain – I purchased a solder pot, and we even bought an electric enameled wire stripper (if results with thinner wire).
There are a lot more pictures over in google photos
When it comes to making your own launcher, it’s hard for me to do much better than the Instructable I put together a few years back.
If on the other hand you are looking to make rockets, fast and furious, check on my video on YouTube is the place to be. There is also another video where I make a high pressure rocket in about 2 minutes.
At RobotsConf in Florida Ben was struggling to find a way to make his bot competitive. All the bots started as identical laser cut kits. Whatever to do? Hairspray! Well hairspray and a pilot light that is. The firebot was born. But it didn’t look the part… but that’s a story for another post.
While working with a prosthetist (someone that designs, creates and fits artificial limbs) to record and analyze the behavior and performance of of amputees wearing prosthetics, we discovered that we could do more than just capture the information with gyroscopes and accelerometers… we could display it in real time. But that was too much for the human eye to handle. Using a programmable LED strip we were able to strobe different colors representing different axes and motions. And by taking a long exposure photograph in an otherwise dark room we were able to capture rather striking images of the exact data we were seeking to plot. It was real life data visualization.
Jenga is a pretty simple game… that gets a wee bit trickier when you can’t use your hands. In particular playing with tongs to handle the dry ice means that if you squeeze too hard the dry ice will squeal as it sublimates under the tongs and the tongs move as you squeeze and the gas escapes. It just seems to make people more nervous, but it looks cool – especially if you add blinking LEDs. Using a mitre saw with a simple jig is a good way to turn out uniform pieces in short order.
The basic flip-flop circuit or astable multivibrator (try telling a bunch of middle school kids that’s the name of this thing). This version was built after the Feltronics Flip Flop, but make so all the components could be used with feltronics. The negative voltage across electrolytic capacitors and the initial race condition meant that this was never the best first contact teaching tool, but that only inspired us to come up with something better. (ssh – this picture isn’t really a flip-flop, can you figure out what it really is?)
Who needs a fiberglass substrate? Paper circuits for the win!
Of course we have made the flip flop circuit many different ways