The Controversy Behind Nike’s Vaporfly Running Shoe, Explained | WSJ

Anything more than totally naked sporting competition is essentially a materials question.

Wooden tennis racquets gave way (briefly) to aluminum and then to composite racquets.

Wooden baseball bats became aluminum then composites.

Similar progressions took place for pole vaulting and nearly every other sport.

In running, however, the materials question mostly shows up in the running shoes, and Nike's Vaporfly is the current materials leader in that realm.

More videos after the jump...

Weird metal that's also glass is insanely bouncy

I've been looking for an amorphous metal demonstrator off and on for a few years but with no success.

There are some samples of amorphous metals available on ebay, but I really don't have any idea of what those metals actually are, whether they're really the zirconium-beryllium-titanium-copper-nickel alloy that Steve describes at 7:10 in this above video.

This video sees Steve explore how to optimize the bounces - which material should the ball bearing be made from, how big should the ball bearing be, how can you measure the number of bounces most easily - which is cute, but the big payoff in the video comes after around 10:00 when Steve explains how materials plastically deform and why amorphous metals don't easily deform plastically.

That's absolutely fascinating, and I even more desperately want one of these atomic trampoline demonstrators.

Feel free to hunt one down and buy me one for Christmas. I'll happily give you my address if you do get ahold of one.

Now I'm curious how an amorphous metal would respond to a hardness test. Would it be much tougher to create a traditional 'dent' from a hardness tester?

(In hunting down more info on amorphous metals, I might've found a preliminary answer to that one on the LiquidMetal website, scroll down partway to find hardness data.)

Here's more info about amorphous metals and a video from Grand Illusions, from whom Steve borrowed his atomic trampoline demonstrator.

• MRSEC at UWisconsin - amorphous metal page
• LiquidMetal - the trade name under which the amorphous metal is available
• A white paper about the Atomic Trampoline from UWisconsin & Arthur Ellis
• LiquidMetal's wikipedia article
• "The Case for Bulk Metallic Glass" paper from Science Direct
• A white paper from Taylor Edge electronics about metallic glasses and the atomic trampoline demonstrator
• Information about vitreloy, a different commercial name under which metallic glass has been available

Are solid objects really solid?

I am coming to love Alpha Phoenix's videos more and more with each video. He explores concepts that are often ridiculously subtle until you think about them a little more deeply, and he uses them to explain the details of the materials around us.

In this video he asks how long it would take for a force - a hammer hit in this case - on one end of a bar of steel to be felt on the opposite end of the bar. It's something that seems obvious at first because a push on one end of a steel bar is 'immediately' felt at the other end of the bar. That's true on the scale of a bar a couple of feet long and with the time scale that you and I notice things, but Alpha Phoenix uses far faster measurements than his eyes and proves that the force isn't felt 'immediately' on the other end.

And then he explains why this happens using magnets and springs representing the particles within a solid and does it brilliantly.

Now I just want him to make more of his videos. At his current pace, he's putting out a video a month or so which leads to high quality videos, but I just want more of them.

Nitinol: The Shape Memory Effect and Superelasticity

The initial part of this video from The Engineering Guy isn't anything new to most of us teaching material science: NiTiNOL changes shape as its temperature is raised. From there, though, this video does a great job showing animations and graphics explaining what's happening within NiTiNOL when its temperature changes. 

I haven't heard the explanation of the mirrored or non-mirrored rhombic crystals. That's really interesting, and I'd admittedly like to get some confirmation from an expert that it's not an over simplification. 

Bike tires that last a lifetime without any puncture or degradation are inspired by NASA's rover technology

 

I've posted about the NASA rover's memory metal ties on the blog before, and we certainly know that technology developed for the space program often makes its way into our everyday life. So it's not a total shock that those tires would be finding their way into use here on the Earth.

But I wouldn't have bet that the first Earthly use for this tire technology would be on bicycles.

Who knew?

As this article writes, "The airless METL bike tires are crafted out of the Shape Memory Alloy Radial Technology (SMART) – made from strong (like titanium), lightweight yet ultra-elastic material (like rubber) known as NiTinol+."

The METL tires come from The Smart Tire Technology Company and aren't available just yet, though they are taking names for the waitlist. I'm really curious how much those tires would cost and whether they would adaptable from one bike to the next one that a cyclist would purchase. Otherwise, it might not necessarily be a great investment.

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

The Physics of Slingshots 2 | Smarter Every Day 57

I keep wanting to tell Destin that he's gonna shoot his eye out.

But it looks like he still has his predator vision at the end of this video, so that's his business as to whether he wears goggles or not.

At 2:13, Destin shows a graph of the potential and kinetic energy of the ball/band system as the band stretches and releases.

At 4:39, he then uses actual data/video to show that a tapered slingshot band accelerates the bullet faster than does an un-tapered band.

Then, at 5:00, our favorite - the stress-strain curve - shows up.

Sadly, some of the links in the video description to learn more about hysteresis, for example, are dead.

Destin got two videos out of his visit with Jorg (check the slingshot channel for even more). The other video doesn't have as much material science content, but it's still fun, and it shows some momentum and energy calculation with a gigantic slingshot.