How Hard Can You Hit a Golf Ball? (at 100,000 FPS) - Smarter Every Day

I'm not always down with Mark Rober's videos. He tends a bit much toward goofy, seemingly-feigned excitement for my tastes, and he tends to bring this out in Destin, too. I'm starting to see a trend in YouTube videos that could easily be made about 30% shorter if they'd just edit out the people going "Whoa!!!!!!!...Yeah Baby!...Look at that!".

But...

To hit the serious matsci/science content in bullet points here...

• 6:25 - compressed golf ball with elastic deformation
• 7:05 - "The ball is hot." - transformation of kinetic energy into thermal energy
• 7:30 - destructive testing and inelastic deformation
• 7:40 - Destin actually says, "an area of physics called material science" and demonstrates elastic and plastic deformation with a 'force-distance' curve (pretty much a stress strain curve). He also compared the curves for a generic metal and a generic plastic, then real and practice golf balls
• 9:15 - We see a plastically deformed but still intact golf ball, one that was hit somewhere above 300 mph against the anvil.
• 10:05 - 50-year old golf ball hits the anvil and is obliterated, apparent source of the apparently-color-enhanced video still above

How To Stop a Colossal Bridge Corroding

Every year a trillion dollars are spent in the US (source) in dealing with corrosion (prevention, repair, research, down time, etc).

I'm glad Britain is spending a few dollars as well, particularly in keeping the bridges upright a little bit longer.

Here Tom Scott goes through the process of checking the cables of the Humber Bridge for corrosion ten years after a gigantic dehumidifier was installed for the air inside the cables.

World's Lightest Solid!

I've written about aerogel before (and perpetually mention the demise of my one piece).

But I haven't shown a video that uses a FLIR camera (1:00) to show the heat zones as they insulate a chocolate bunny from a bunsen burner using aerogel, where they show the industrial process of making aerogel (5:25), or especially where you actually get to see a supercritical fluid through the window (6:25 - the absolute highlight for a teacher who used to teach phase diagrams in AP chemistry), or where you get to see a mid-process 'wet' aerogel filled with alcohol (4:50).

If you happen to follow both of my blogs, you might see this double posted because of that supercritical fluid bit.

Seriously, Rebecca, you'd have my heart if you bought me some new aerogel.

Can You Swim in Shade Balls? - Veritasium

If you want to know why Dr Derek is head-deep in what looks like a ball pit (a la xkcd), you probably should watch this video (which might lead you down the rabbit hole into a fascinating video about what going viral and chasing YouTube's algorithm means for YouTubers).

But if not, you should check out the fifteen seconds starting at 2:40 above. Dr Derek mentions that the shade balls (not actually play balls) have "sort of arranged themselves in crystal structures where they're close packed, and there are boundaries between those grains".

There are a few more mentions of close packing efficiency (at 3:55) when it's mentioned that the spheres only cover 91% of the surface area, and you can see the grains reform as Dr Derek and his friends swim through the pool. There's also some physics mentioned about drag being proportional to the square of velocity.

Mostly, though, this is a stunt video, but c'mon, who needs a crystal demonstrator?

Becky, can I put a pool in the budget for next year?

August 3, 2013 Stick Bomb Tutorial

Ok, this might be a bit of a stretch today but stick with me. (groan)

We study tempered glass in material science. We go through the process of tempering - molten glass directly into cool water. The outside hardens quickly, locking in its shape while the inside is still molten and expanded. As the interior cools then, it tries to shrink and can't. So the inside is in tension - pulling inward - while the outside is in compression - being pulled together tightly by the inside glass.

If you don't know what I'm talking about or need the most awesome tutorial and visual of that ever, check out Destin's Prince Rupert's Drop video at 3:25. Destin also mentions that the Prince Rupert's Drop stores mechanical strain energy.

And for some reason this year when teaching tempered glass, the idea of a stick bomb popped into my head. I remember making very basic versions - of these when I was a teenager, but I never made anything approaching the long chains that you can see in the video up above. I am pretty sure, however, that the stick bombs also store mechanical strain energy in their structures - just like tempered glass does.

And it's a heck of a lot easier to have the students make in class than tempered glass is.



Though you can have the students make Prince Rupert's Drops.