.50 Cal vs Ballistic Window HARDCORE Slow Mo - Smarter Every Day 187

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. 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 strengths. 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, a 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 so pretty. Sweet!

Okay, weapon's clear! Dude. Okay, real quick. I want to 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 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 buttons. There you go!