Why do Baseball Bats Break?

Oh, hey, Grady. Good to see you.

In this video - about why major league baseball saw a sharp uptick in broken bats (and subsequently an uptick of injuries caused by flying bat shards) in the early and mid-2000's - Grady gets into the differences in ash (the wood used to make almost every pre-2000 bat) and maple (a wood that became popular - not poplar - with ball players in the early 2000's after Barry Bonds used one to break the HR record).

He then goes into the non-isotropic nature of wood and how ash and maple are very different. I guess the lessons learned in making ash bats didn't translate cleanly into making maple bats. It doesn't mean that maple bats are inherently less safe, just that they need to be made - and particularly marked - differently than do ash bats.

Really, changing the material requires changing the production and use strategies for that object?

Who would've guessed it?

The Astounding Physics of N95 Masks

As far as I'm concerned, you can chuck the other two N95 mask videos that I posted earlier. This one's way better than either of those.

It does, I'll warn you, have a statistically-backed, pro-BLM message at the front end. If you want to avoid the controversial subject, skip ahead to 0:10. (That being said, I'll be playing the full video in class, but that's your call to make in your room.)

From there, the minute physics video explains how N95 masks are less like a strainer or a screen and more like a sticky spider web. Those spider webs - in the N95 masks - are really sticky because of the van der Waals force and the permanent charge imbalance  of the fibers. 

Seriously, this video is the best at explaining how the masks work.

You should watch it...

...and (if you're reading this in 2020), you should wear a mask - even if it's not an N95 mask.

Volcanic glass spray shows promise in controlling mosquitoes

Source - https://phys.org/news/2020-06-volcanic-glass-mosquitoes.html 

So, pesticides are bad.

I know, feel free to applaud for taking such a bold, controversial stand.

They're bad for pests, for us, and generally for the environment.

But there are a few pesticides that aren't terribly bad for us or the environment while still maintaining the 'really bad' nature for pests. There's diatomaceous earth, for example, which works by grinding away at insect exoskeletons but is relatively harmless to anything with skin and an endoskeleton.

In the linked article from phys.org, experimenters applied a spray of perlite, a volcanic glass, and water and measured its effectiveness in killing mosquitoes - primarily malaria-infected ones.

Their results suggest that perlite is highly effective - as high as 78% mortality rate six months after application, and the perlite seems to be safe for people in the huts. According to the article, the mechanism of mortality is that the perlite particles simply dehydrate the mosquito after they're picked up. The mosquitos also didn't show any indication of learning to avoid the perlite-sprayed walls or building up a tolerance to the perlite.

The article might say that perlite isn't a silver bullet, but early indications looks to me like it might be.

How Weed Eaters Work (at 62,000 FRAMES PER SECOND) - Smarter Every Day 236

I've spoken of my love of Destin before. One of the things that I love most about him is his scientific curiosity. He's willing to point a slow-mo camera at just about anything and set up some experiments to teach himself more about whatever that camera points at. It's kind of awesome.

In this one, Destin points his Phantom high-speed at weed eater string to see how the string cuts blades of glass (cut or rip? delaminate or clean slice?) and breaks against various wire fencing materials.

We could do a lot worse than show this when talking about destructive testing in class.

There's also a second video that tries to figure out which shape or string is best. He comes to a conclusion, but I'm not sure he does nearly enough experimenting and variable isolation to actually justify the conclusion he comes to.