Posts Tagged: #randomactofscience
popping popcorn
In a typical class or Friday night, I’ll pop popcorn and wonder: What happens to the stuff of the popcorn kernel as it is transformed into the morsel of popped corn that I can eat?
Those two “states” of the corn are really different. One I can eat easily, the other seems impossible and would break my teeth. So what happens to that stuff as it’s heated? In particular, does the stuff that’s there stay the same or does it change? I know that it’s different in some way, but how do I model the matter of this popcorn and where it goes (or stays)?
There are probably lots of great models and lots of great ways to think about this. As you do, you could use your model to predict if the kernel changes its mass as it is popped, or does it stay the same? And, if it does change, does it get more or less massive? And, regardless of what happens, what does that tell us? How do our models help explain what’s going on as popcorn is popped?
I documented this mini-investigation in a video:
Full video of my popcorn investigation.
I’m adding some space here so that there aren’t any spoilers. Below are a few screen grabs of the video that capture some key moments in my science and acting career.
Pointing out the kernel. It’s hard to see, because it’s small. That’s actually part of the challenge.
I thought I could weigh a single kernel to compare to after it popped. It’s really hopeless because the kernel is too small, and …
…wouldn’t it be a better idea anyway to have a bunch of kernels, in case some don’t pop or something else weird happens. Plus, this is easier to weigh.
The bucket by itself was 95 grams, but with the added kernels the total mass was 166 grams. So that means that the kernels by themselves were 71 grams, but it’s easy to just keep track of the popcorn in the bucket since that stays the same.
Live action! Pouring kernels into the air popper! (It’s probably important that I was using an air popper without any butter or oil.)
Popcorn! In the video, I speed up this part of the footage, which is kind of fun and convenient.
[Drumroll, suspense, etc.]
Final massing of the popped popcorn with the bucket. What happened?
A summary of our data.
Huh.
That’s a loss of a few grams. Doesn’t seem like much, but it’s pretty substantial in comparison to what we started with–about a 10% loss of stuff. So where did that go? It could be mistake, but this was monitored and it’s repeatable. We also talked about it being air in the kernels, or some kind of chemical reaction, or some loss of liquid water that could have been in the kernels. Or maybe something else.
There are a few things that could be helpful to know. For example, the density of air is something like 0.001 gram per cubic centimeter; and the density of water is about 1 gram per cubic centimeter. That helps us think about how much stuff we could lose of either of these and what we might expect that to look like.
This quick investigation was done with an air popper, but when I pop popcorn at home I do it over a stove and have a glass lid. This way I can see a little bit more of what’s going on. So, the other thing I could contribute is what it looks like when I pop popcorn. I recorded the video and put it on the internet, because I figured that was what the world needed:
Here’s few highlights from the video, just for posterity:
drinking bird
I often host a lab where we study the Drinking Bird in its native habitat. But, in case you don’t have a chance to be in my lab and you don’t have your own drinking bird, here’s some video you can analyze. The bird goes through two of its cycles in this clip, and I repeat those cycles at high speed so you can see things in a different way.
A drinking bird is very simple, which makes its actions that much more interesting, I think. What do you notice? What do you wonder about? Can you trace out cause-and-effect rules in the bird and its motion? Can you create a model for how it’s working? In particular, how can something just move (and there are a few different motions in this bird) when it isn’t hooked up to anything else?
Appendix:
In case you need more footage of the drinking bird for longer amounts of time, I have about an hour and 15 minutes of video, both in real time and at 10x speed:
liquid motion
What makes up matter? We can’t see it directly, but observing some details might help us imagine what’s going on at a deeper level.
I have two glass bottles of water that I drop red dye into. All the water came out of my faucet, but the two bottles behave differently. What do you notice? What do you think might be happening? How do you picture or model the water and dye interacting? How could you investigate this on your own? What would you try?
sound tubes
Different musical instruments work because they play the note you want to hear. This seems obvious, but it’s no small thing to make something play exactly the right note, and leave out all of the other noise. How do they do this?
Instruments are made from lots of different stuffs and geometries. Some things, like violins and guitars, use tight strings to create their notes. Tuning forks and the reeds of a harmonica use vibrations of solid materials with specific lengths. Other instruments, such as organs and clarinets, produce the notes in a tube of air. That’s the kind of instrument I’m playing with here, except my tube is a simple piece of pipe.
You might not have a tuning fork to create this phenomenon, but is there something else you could do to make a tube sing? What other instruments could you create? What do you think the sound waves in the tube look like?
upward liquids
A lot of people don’t believe me when I tell them this, but I truly don’t understand how water crawls up a paper towel or string or piece of cloth. How does it get the energy to do this when it’s just sitting there; and the towel is also seemingly passive in the whole affair?
I’m a physicist and I work with many like-minded scientists. When I ask them about this phenomenon, they realize that it’s not all that simple, but probably it has something to do with electric forces in the towel and interactions with the water. I’m sure that this is part of the answer. But even so, I’m happy to admit that I don’t really understand it.
So, I assign the problem to my students and ask them to start to investigate different features of liquid absorption. They think of much better investigations than I would, and when we share these we start to come up with more ideas. To get them started, I’ve created this timelapse video of water moving up a cloth:
I thought my idea to speed up the video and include a clock in the frame was clever. I’m proud of that old-school technique.
What do you notice? What wonders strike you? What investigations could this spur? This is just the beginning.
Here’s what the scene looked like the following morning:
And then, later that morning, I detached the cloth and set the loose end on the table. It was originally dry, but then this puddle started to form:
Epilogue
In my classes, I see lots of really great examples of how this phenomenon can be turned into a research project with lots of different variables. Researchers create all sorts of different investigation designs with interesting variables and creative methods. This time-lapse video that Micah created gives a good impression of one of the hundreds of ways the climbing fluids can be studied, and it’s fun to see the process overviewed in just a couple minutes:
static cat
I like to tell students that cats love to do physics. Seldom do I actually get a chance to show them, however.
Thank goodness I can make videos so that I don’t have to bring Gus to class with me. Here’s some work we were doing together to investigate how balloons and cats stick together.
hummingbirds in slow motion
I don’t have much to say about this except I really enjoy watching hummingbirds. Even in slow motion they’re still really fast. I like the way that they turn their wings and use their tails to maneuver, but I’m especially fascinated with how still their heads are while everything else is moving:
balancing acts
If you see me in front of an in-person class and I have a meter-stick, you’ll often witness me trying to balance it in various ways. The most impressive and kind of magical way to balance a ruler, stick, baseball bat, etc., is using this trick of sliding your fingers towards one another. They naturally meet up at the exact balance point, even when the object is lopsided. Take a look:
I also like this video because it shows me messing up and dropping stuff, and there’s a great cameo of our puppy, Nina. Oh, and the intro and outro features my favorite band.
What other objects can you balance? Can you create an investigation around finding the balance point of an object under different conditions? How would that point shift if I kept adding weights to one end or another, or to a different spot? What other strangely shaped objects would balance this way?
ice melting
On hot summer days you might really enjoy a glass with ice, just because you like a cold drink. But have you watched the ice in your glass up close?
I like investigations just watching ice melt. By taking some video and speeding it up, you get to see the whole process in just a few seconds. Here’s an example where we take ice that’s made from water with red dye. This way, as the ice melts you get to trace where that new liquid goes.
When you watch the ice melt, it’s funny that it goes from the top of the glass and falls to the bottom. What makes it do this? Why did it float in the first place? What would make it sink?
There are other liquids besides water that we can’t drink, but we can still put ice in them (as long as we’re very careful and label these liquids so we don’t accidentally put them in our mouths). I decided to compare what regular (water) ice does when it melts in water compared to when it melts in rubbing alcohol (isopropyl alcohol) that you can get at a pharmacy or grocery store.
Here’s a fast timelapse of these two, side-by-side. We think there’s a lot of interesting things going on, even at the beginning before any melting has happened. We added some salt at the bottom of the isopropyl alcohol to make it a little easier to see and to make some salt water as the ice melted.
I really enjoy making these videos because then we can replay these episodes really quickly and make comparisons. But it’s also great just to see how ice melts in different ways in real time. You could make videos; or, you could write notes or take pictures or just observe and talk to others about what you’re seeing. You might think of other variations on this theme.
sun circles
It was a nice morning, and I thought it would be a good choice for me to sit in my backyard and read a book. But it’s easy for me to get distracted, and soon I was really interested in a spot of light that was on my chair:
(For more information about this great book, see:
https://www.hepg.org/hep-home/books/science-in-the-city)
I wondered what made this spot and I turned around to see how sunlight was coming through this tree behind me:
What I think is really amazing is how all of these leaves and the gaps between them are different shapes, but the light coming through makes circles. I used a white notecard to find more of them:
You’ve probably seen spots like this before, maybe without even knowing it. (Once you start to see them in a few places, you might have a hard time not seeing them!) Sometimes under a tree we say that there’s “dappled light,” but it doesn’t matter what you call it. There are funny shapes and a kind of light that photographers and artists like, all made by the overlapping circles of light like this.
Can you find circles of light like this in other places? What do you think makes these circles? Why are there so many? Are there other ways to make these sunshine spots? Could these circles be a picture of something else?