There is a particular physical phenomenon that I've always wanted to see but I've never been able to quite set it up.
That changes today.
This is a piece of bullet-resistant acrylic specifically rated up to nine millimeters.
This is a phantom V 2511, stupid fast frame rates.
I've always wanted to see the specific spot where a bullet
Interacts with a piece of armor right at the nose of the bullet
Think about it that moment in time where the tip of the bullet hits the strike surface is so small in time
That it's hard to imagine the physics
That's going on
The good thing is now we can visualize it in order to do this you have to line up the flight path of the bullet
Directly in line with the camera and not only that I don't want to see a 9-millimeter try to penetrate this acrylic
But not do it. I also want to see what it looks like when you actually get through hey
It's me Destin welcome back to smarter every day. I'm here with Gavin. Hello and Dan from the slow mo guys
Roll tide
Roll tide and what we're gonna. Do today is something. I've been wanting to do for a really really long time
170,000 frames per second you think oh, I'm at 120 at the moment we could go up to 170. Let's try it okay
We're gonna use a wireless trigger on the high-speed because we don't want to be anywhere near a bullet hitting bullet-resistant glass
So I've got a shield for the camera and we use a wireless trigger to be safe
You actually know how to run the Phantom well yeah, we're all going to our strenghts. Yeah exactly
Where's Dan?
So it went in and it mushroomed out and it kind of peeled out the edges on the outside there, but that one little spot that
You can see you can see through it. This is weird science time here
I thought that the exact spot the bullet touched the acrylic first would suffer the most damage, but clearly that's not happening
I've got to thinking about this
And I think it has something to do with an old word
Called a frustum according to this old dictionary a frustum is a cone with the top cut off
Let's imagine that this is our acrylic plate the bullet interacts with the top of the plate at the point of impact right here
That force tries to punch its way all the way through the plate now long time ago
Engineers figured out that stress isn't transmitted through a plate like a cylinder
It's actually something called a pressure cone every material has its own compression cone angle
This is what I honestly think's going on here stress is equal to force divided by area
I know that much as the force is
Distributed over a wider and wider area as it goes down through the acrylic you eventually get to the point with a nine millimeter
where it no longer has the ability to fracture the acrylic the stress isn't high enough however a
50 Cal would definitely do that because there's a much larger pressure cone it gets further through the material
We basically get to the part where it'll just break out the back so there. There's a larger pressure cone
I've set some big words. We've got a little bit. I think that means we get to play with the 50 Cal now
The slow-mo guys video
Here we go hot
This cone of the front is like ejecta material being forced out of a meteor impact
Where's this stuff in the back? Is that cone is the stress propagating through the material? That's that's so pretty
Sweet okay
Weapon's clear!
Dude
Okay real quick. I wanna say. Thank you to the company that gave us the bullet resistant glass to be clear
It's not supposed to protect against 50 Cal rounds. It's just 9 mil stir not correct
Not 50 Cal correct, but we'll leave a link in the video description for those guys
So we can all agree that that's stinkin awesome slow-mo right, but there's more to it than just cool footage
I want you to think about
Fracture mechanics think about the pressure cone as it goes down through material
And how it has to get above the minimum fracture stress in order for it to do its thing
So just think about it on a deeper level also
Obviously this was a collaboration video. I'm actual real-life friends with Gavin and Dan super cool dudes the way
I'm just gonna go straight to the front door here the way a
collaboration video works is the hope is that more of you would subscribe to smarter every day and more of you that watch smarter every
Day will go subscribe to the slow mo guys
So please consider subscribing to this video if you feel like it earned it
but
The most important thing here is for you to go watch the video on the slow mo guys and subscribe to them
I want to say thank you to Gavin and Dan the slow mo guys for coming out and helping
Gavin knows what he's doing and Dan knows his way around a weapon as well
Play to our strengths Yeah play to your strengths. Well. But we let Dan come out anyway, so
If you wanna check out some stuff on their channel. What are you doing over there?
We're using a mirror to shoot the camera directly in the face with a 50 Cal
Hopefully see the bullet coming towards my lens an ambitious shot was it uh seven five Orion where the guy was
Shooting the German was shooting with a sniper rifle
It just sees the guy the flash of the weapon that goes into the scope of the guys
The Germans right here less violent version of that pretty much that except no one dies
This is them shooting in the intro for their video right now. I think you'll dig it. Go check it out anyway. I'm Destin
You're getting smarter every day. Have a good one
So now is the part of the video where I put subscribe buttons in the corner?
And hope that you will subscribe to them
And then I do something interesting visually interesting in hopes that you will
Have your attention drawn over there and click one of the subscribe buttons
so this is my attempt to be visually interesting and
Convince you to click the subscribe my buttons
There you go