- When you're driving,
you should feel pretty safe.
After all,
you're surrounded by a medal cage
that's been designed to protect you.
But what about the glass?
The glass in your car
is different.
Where does it come from?
Why is it different than this glass?
(glass shatters)
Let's break some windows.
(hip hop music)
Pop!
This is cars
down to the atom.
Science.
(hip hop music)
In order to understand the special glass
that makes up your car,
first,
we need to understand regular glass.
Now, you probably know that glass is a clear solid thing
that comes from sand,
but if you don't,
glass is a clear solid thing
that comes from sand.
Sand is high in an element called silica
and when it's super heated,
it melts together and it dries pretty solid,
but what if I told you it's not a solid.
Glass is what's called an amorphous solid.
It's kinda like it's the slowest flowing liquid
you could ever imagine.
It's like when you pee after a night out of heavy drinking.
For sand to melt,
it's gotta get up to 2800 degrees Fahrenheit.
Holy (beep).
At that temperature,
sand is a liquid and it can be molded,
stretched or blown to give it any number
of different properties.
This is a forge I made,
I looked it up on YouTube and you can too,
but don't,
because it's stupid.
(light classical music)
(banging)
Hey!
Turns out making glass is harder than I thought,
but the sand did melt and it's shiny.
As you can imagine,
you wouldn't want this making up your windshield.
So how are the windows in your car different?
Well, first let's talk about the windshield.
Modern windshields are so strong
that they can withstand over 2,000 pounds of force.
They even play a role
in the structural rigidity of your car.
In 1903, a French chemist accidentally dropped a beaker
that was covered in nitrate plastic.
When it hit the ground,
it broke but it didn't shatter into pieces.
And safety glass was born.
If you've ever broken a windshield
or seen one break in the movies,
you'll notice that it shatters
but won't go anywhere.
(bang)
(beep)
The glass in your windshield is actually two pains of glass.
It's got a layer of glass,
layer of vinyl,
and another layer of glass.
The layer of vinyl makes sure
that everything sticks together.
It doesn't shatter all over the place
and stick in your neck and kill you.
(beep)
(bang)
- Down here?
- We're gonna get fired.
(laughing)
The glass in your side windows is different.
It's strong because of the way it's cooled,
it doesn't have any vinyl in it.
When it breaks,
it smashes into pebble sized pieces
so it does less damage to your face and family.
The process of making glass harder is called tempering
and that's the key to making your side windows safe.
Tempered glass is heated and formed
much in the same way that the windshield is,
but when it's cooled,
it's super cooled.
The surface of the glass is cooled so quickly
that it shrinks.
This creates a compressive force on the glass inside
making it stronger.
Kinda like pressing on the outside cans
keeps the middle ones from falling.
The glass on the inside is cooling at a different rate
and it's trying to expand
against the shrinking edges.
This creates a tensile force,
further improving strength as the glass cools.
These pulling and pushing forces
make the glass up to 10 times stronger
than non-tempered glass.
Kind of like the contrasting forces of good and evil
keep our universe from falling apart.
- [Voldemort] Avada Kedavra!
- It's super hard to break,
even with a hammer!
(bang)
What?
The hammer didn't work because
the force wasn't focused enough
to break the tension that keeps the glass together.
To break it, you need somethin' sharp enough
to get in between the glass molecules.
This is a bit of porcelain
that I cracked off a spark plug.
And I got plenty of spark plugs lying around
'cause I'm a car boy.
When the porcelain shatters,
it's edges are super super sharp,
like micron sharp.
When this hits the window,
the force will be so focused,
that all the compressive and tensile stress
will be released
and it'll break.
The window will actually use its own energy
to destroy itself.
Just like James Pomphrey.
(banging)
(glass shatters)
(beesp) nuts.
(laughs)
You can see that
that force is still being released.
The glass is actually exploding from itself.
There's so much energy in the tempered glass
that it's like it's alive.
That is nuts.
I mean, it's just glass,
but when it's in your car,
you can really see how dynamic it is.
Now you know not just that
the glass in your car is different
but why it's different from other glass.
Cars are amazing.
Everything is amazing.
You're amazing.
(beep)
It's super hard to break,
even with a hammer!
(bang)
(laughter)
Thanks for watching everybody.
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Okay, don't tell my wife I did this.
I'll see you guys next week.