Revisiting Gelatin

I don't think I've put this video on the blog. I got tired of just dropping one ball on gelatin - so here's a slow motion study of four balls dropping onto gelatin. I like the individual impacts and then the interference created by overlapping shockwaves:

New Favorite Thing

As much as I enjoy filming water balloons bursting in slow motion, I am always interested in trying new approaches. Perhaps one of the best is achieved by adding a little bit of gelatin to the balloon. At least, I'm a huge fan of the idea. The only drawback is that they take about four times as long to clean up.

So, this happened:

Last weekend was somewhat epic. I got some sweet high speed video footage of a male bluebird attacking its reflection in our window (update: it's still seeing something, so I've got to upgrade my deterrent system). I love the aerodynamics inherent in this video.




I was also invited to visit a beekeeper and shoot high speed video of bees pouring into a hive.


Here's the result:


It was a fantastic weekend. I really want to get some more bee footage - while my research on live snails may not lend itself to high speed video, insects certainly are. I'll leave you some additional pictures of the day:

Moar Stream Table SloMo

Thurs-Demo: The One that goes with the flow

This week, we're mixing the slow and the fast. Our Em2 stream table is an amazing model. I think it's the best fluvial system-in-a-box models out there and I wish that everyone who do outreach/education/research about streams and the environment had one. I understand that these things aren't cheap and if there's one thing most environmental educators are familiar with, it's lack of spare dollars. Which is why I appreciate the "open source" approach that Steve and the LRRD team bring with their stream tables. A fully equipped Emriver model may cost a few thousand dollars, but the knowledge the LRRD has gained from the model development is priceless.

With that knowledge comes a willingness to share and collaborate. I even hear they're looking into ways of sharing more than just expertise (but I don't want to spill their beans - if Steve wants to provide more information, go ask him about it). I don't want to sound like I'm trying to sell you a stream table. But I do want you to think about how you can use the ideas generated by these stream tables. If anything, I'm trying to sell you on the idea that stream tables can be more than just sand in a watertight box with an aquarium pump.

Okay, back to my demo. Over the last semester, I tried taking time-lapse photographs of the stream table in order to show some long-term process over a shorter time span. Recently, our department acquired another amazing tool - a high-speed camera. It takes thousands of frames of video every second and expands a very short-term process into something we can see over a longer time span.

So why not see where the high speed camera can be used on a system that normally people associate with very long-term processes? I present to you turbulent flow of some Emriver plastic sand in an open channel flow:


And, here's a bank collapse at 1,000 frames per second. These are tricky, since you don't know exactly where the bank is going to collapse and the high speed camera is fussy enough that you need to have everything locked down while shooting:

Feeling Blue

I've got an interesting problem. We have a very happy pair of Eastern bluebirds who are checking out the box in our yard (and probably the one in our neighbors). Apparently the male has decided that his reflection in our big living room window is a rival. So he spends quite a bit of the morning carefully eyeing our window and occasionally flying right up to the window.

This kind of behavior can be rather stressful on the bird - it wastes needless energy defending territory against an imaginary rival. There's also a chance that the bird could injure himself if he gets too enthusiastic. So I've been trying to find ways of dissuading our little blue ball of piss and vinegar from wasting his time with the window. Window clings didn't seem to work. Putting something opaque on the inside of the window wasn't very effective either. I even moved the mealworm feeder they use across the yard. But he keeps coming back.

. The picture above shows the crop netting I put up. But he's found there is a spot on the side that he can still get to. But, it is keeping him from hitting the window with too much speed. I'm going to have to experiment with stretching the netting out more, but this seems to be something of a compromise.

One of the benefits of having feeders near the window is you get to see the birds. And, if you're so inclined, photograph/videotape them. The footage in the video below was taken with my own Canon 7D and two cameras from our department: a Casio Exlim ZR100, and the memrecam gx-8.



While the memrecam is a bit out of the price range for the average person (most models cost more than a family car), the Casio Exlim is pretty cheap. And the 240 fps video is pretty good. Not cinema quality, but it's perfect for seeing what the birds are up to. Or cats and dogs, people - for those of you with an interest in biomechanics, something like the Exlim might be a great research tool.

Thurs-Demo: The One that Spins you Right Round

It was atmospheric circulation week in geology class and this year I wanted to spend some more time on the Coriolis force (more physics here) and how it affects the predominant wind directions in atmospheric circulation

So this was my setup - a couple of foam balls, separated by a spacer made from a cardboard tube. These are sitting in a tray that's attached to a turntable. The tray has a sheet of cardboard at the bottom so that both balls will roll toward the middle when the spacer is removed. Like so:


But, since we're talking about angular momentum and prevailing winds on a rotating planet, we need to rotate the tray. In this case, I put a camera on the turntable so that the tray is stationary relative to the observer:

But, how could I not include some slo-motion video? Here's the setup viewed from above (at 500fps):

Use the Force - the Coriolis Force

I threw together a quick demo for my lecture about atmospheric circulation and prevailing wind direction. I think a more detailed write-up is in order for this week's Thurs-Demo.

Besides, something tells me it's not nearly big enough.

World in a Drop Revisited

I tried my hand at the "world in a drop" again. This time, however, I took advantage of something that a still image can't: motion. The compilation below includes a few of the original setups where I was experimenting with color, plus the last two scenes, where I integrate movement.

"So I was looking at the map..."

It's been about a year since I finished the maps for my friend Kelly McCullough's new fantasy series (Book 1: Broken Blade is out!). A few weeks ago he started a line of conversation that began with "So I was looking at the map..."

I'll let you imagine all the possibilities that could arise. But apparently, I had drawn - and he had approved - placing the Ismere library too far away from the river. I can't give you any spoilers, but suffice to say that there's a key scene in book four that requires the library building to be located by the river, not just the canal (something to do with "living water," but I can't say any more than that).

I guess Kelly had described the library as being near the river, but neither of us had really figured out the sketch had the library "away" from the river before the map was published in the first book.

Testing how a remarkable picture would work

You may have seen this picture floating around the interwebs:

There was a blurb in gizmodo about it, but before I had seen the write-up and the photographer's amazing gallery on flickr, I was trying to figure out if it was real, or perhaps "enhanced" just a bit...

I knew that it was possible to get clear images in a drop of water - they act like little lenses, but seeing details is tricky. A reverse image search in google brought me to the source of the images and confirmation that his setup could produce a picture like the one above.

So of course, I had to try it with the high speed camera to see how easy it might be to capture as a moving image. It took a little experimenting to get the right proportions and the proper focus.


My first nearly successful attempt showed me that my image of the world was too large. Europe and Africa are easily seen, but the other continents don't really show up. On to a smaller map and this time I used just an outline so I could color the land yellow (thereby showing up green through the drop).

A few more experiments and I came pretty close:




Not nearly as "perfect" as the still image, but it shows that I'm on the right track. A few more tweaks and I bet I could get just as much detail out of the drop as the photograph.

Boingggg!

Thurs-Demo Bonus: Into the Mousetrap!

It had to happen eventually. A nice wobbly piece of gelatin, falling onto a mousetrap...

Thurs-Demo: The One With MOAR GELATIN

No time to write up what's going on here, but take a moment to watch how the interference patterns change as the stress acting on the wobbling gelatin changes.

Slo Mo Cat

Pippin is a very cute cat. Even more so in slow motion.

Tiny flying Archosaur

Here's another view of a chickadee at the feeder:


I love how it had to rotate its body to the left to clear the hanger from the feeder and then a few wing beats later it gives a left-wing flap to rotate itself back and start a turn. Then it tucks its wings back and dives out of view.

It also works well on the living.

Took the high speed camera into the sun today. Here's my cat, trying to catch a treat. He's not the best at catching, but he's really good at ambushing treats lying on the ground:



The birds weren't very active at the feeders outside our window today, but I did get a chickadee taking flight:


Clearly, I need to get more video of avian dinosaurs in motion.

Springs! Peeps! Science!

Okay, you've been waiting long enough. According to my clock, it's Saturday. Here's a celebration of the seasonally specific sweets:


Enjoy your holiday weekend! And don't eat too much sugar - or you'll end up like a peep under a vacuum.

Plop!

Dropping a steel ball into water, now with flocculated mud!

Nature Abhors a Vacuum, eh?

So, they say nature abhors a vacuum and that peeps are "unnatural" in every measure. This gives me an idea...

Check back on Saturday :)

Thurs-Demo: The one with the Backstage Tour

I've had a few people ask about the general setup that we use for high speed videography. Here's a little visual tour of the setup and results of some gelatin experiments. If you consider yourself a Strain Junkie, it's best that you give yourself a little time to watch closely...

Gelatin at 255 Hz

Placing a tuning fork on gelatin gives you some lovely wave patterns. I don't know what I was expecting, but I'm rather pleased with the result. I need to spend some time and adjust the perspective, but the results give me some ideas for looking at seismicity in various photoelastic materials...

Duhn-Duhn, Duhnnnnnn...

What in the world can I mean? For the answer, be sure to tune in Saturday.

Nailing Jello to the Wall

Coins in Water

Drop a coin in a well and make a wish? What if you want it to land in a particular spot? I would suggest not dropping it straight on-edge. Little variations can add up to some major instabilities and you get some wacky behavior:


But if you drop it flat, with the face parallel to the water's surface? Much more predicable descent. The little eddies help stabilize the coin as it falls through the water.

Candle Dropped into Water, Take 2

Just to show you it wasn't a one-off fluke, or anything: here's another candle burning underwater for a brief moment before the cavity pinches off and extinguishes the flame.