Dragonfly wing muscles via Ryan Lee Photography on Flickr
Unless you’re already an expert in entomology and mechanical engineering, this high speed footage will forever change how you view dragonflies. As a primer, lets first take a look at the dragonfly in action:
Dragonflies are unmatched in the insect kingdom for precision flight control and efficiency thanks to their two pairs of wings. Managing the flexibility and complexity of the wing system takes some effective engineering. Destin from Smarter Everyday was able to capture some awesome footage of the muscle system on a dragonfly while he was in Peru. He then goes on to explain how the muscle linkage system gives the dragonfly direct control of each wing in both directions. He also shows some flow footage to prove that flapping the two pairs of wings out of phase by 25% nets a 20% flight efficiency for the dragonfly. The Mechanical Engineering doesn’t stop there as Destin examines the heavy spots built into each wing to control its natural frequency of vibration.
Destin from Smarter Everyday just got back from a trip to the jungles of South America to capture some high speed footage of macaws and parrots. He was helping researchers figure out some odd feeding habits caused by a mineral shortage on the western side of the continent. It turns out that the moisture required to sustain the rain forests comes from the Atlantic ocean to the east. By the time it reaches the west coast of South America, the sodium content of the rain has dropped to almost nothing. The macaws and parrots then don’t get enough sodium from the fruit that they eat and have to resort to eating clay.
Of course since Destin is an engineer by trade and nature, he went through the footage to see if he could learn anything about bird flight. When birds glide, their wings have the same foil shape as airplane wings:
You all knew it was going to come to this. In my bid for infinite internet fame and glory I will now be posting a cat video. What we’ll be talking about today is one of the universe’s great mysteries. How does a cat always land on its feet?
Before you start the video, here’s a little background information on Moment of Inertia. Don’t worry, it’s not nearly as complicated as it sounds and you already intuitively understand it from your time on the playground as a kid/kid at heart. Lets start with the conservation of energy. Lets say you have two boys sitting on skateboards that you are going to push down the sidewalk. One of them is skinny and one is fat. If we give both kids a push with the same amount of force, which one will go faster? Well that’s easy; the skinny kid goes faster because he has less mass. You could even go as far as to say that the fat kid’s extra mass makes him resistant to acceleration.
OK, now lets take that same concept and apply it to the merry-go-round. With the kids on skateboard we were looking at their linear speed rolling down the sidewalk. On the merry-go-round we’ll be looking at how fast it’s spinning. The two cases we’re going to compare are when everybody sits in the center of the merry-go-round vs. the outer edge. Even though the merry-go-round passengers weigh the same in both cases, the merry-go-round is easier to turn when everybody is sitting in the center because it has a smaller moment of inertia. The energy put into spinning the merry-go-round results in a higher RPM just like skinny kid went faster on the skateboard when we pushed him. When all the passengers move to the outside, the moment of inertia increases and the merry-go-round becomes more resistant to gaining RPM’s just like the fat kid on the skateboard was resistant to acceleration. So the next time some weirdo asks you about the moment of inertia of something, all you have to do is think about how fat the merry-go-round is.
Now watch the cat video:
You can think of the cat as having two merry-go-rounds attached to its spine, one from its front legs and one from its rear legs. Spreading one pair of legs increases their moment of inertia which gives the cat something to “push off of” to rotate the other pair of legs even though it’s free falling. This gives the cat the ability to rotate each pair of legs so they’re always pointed at the ground. Unfortunately this means there’s no mythical spinning force that causes cats to always land on their feet. That doesn’t make the concept of the buttered-toast-taped-to-a-cat perpetual motion machine any less hilarious, though.
Lets say you wanted to teach kids about why heat cycling new tires is important. It’s up to you to impart important fundamental gear head knowledge to these blossoming young minds. So how do you do it? Maybe we should sit the kids down in the classroom and lecture them about the polymer chain structure in rubber that heats up when distorted. Chances are they’ll end up texting their friends about how much they hate you. You might even make Twitter for being the heinous old person who was forcibly torturing them with the atrocities of totally lame science stuff.
There’s a better way to learn about how rubber works with little risk of being labeled “cray cray”, at least not the bad kind. It involves shooting slingshots, preferably with a huge German dude that runs the world’s largest slingshot forum and builds crazy new slingshots every week for his YouTube channel. Destin of Smarter Everyday did a collaboration video with Jörg Sprave of the Slingshot Channel to explore how to get the most out of a rubber band.
Lets talk about the two questions at the end of the video. Continue reading →
If you enjoy figuring out why the things in the world around you work the way they do, you should subscribe to Smarter Everyday on YouTube. The host is named Destin and he has set out investing money into these YouTube shows so that he can educate the masses and put the proceeds from ads and donations towards his kids’ college funds. He’s a Mechanical Engineer by trade and education and he has a knack for making engineering interesting. For the last couple of months, Destin has been posting a series about the physics that makes helicopters work. It’s really fascinating because they’re capable of a lot of mind blowing stunts and the way they work is different from how you probably intuitively think they do.
Part 1: Introduction
Destin introduces us to the series and his buddy Carl Groover who flies remote controlled helicopters for the Curtis Youngblood team. Watching Carl at work is a pretty eye opening experience in terms of what a helicopter can and cannot do.
