Hey, Vsauce. Michael here, and today I'm in my apartment.
But when I was in Kansas with family my dad lit off what is known as a quarter stick.
But don't worry, absolutely no children were around.
Okay, look, the point is that today we're going to talk about explosives.
Let's begin way down the scale with black powder,
or smokeless powder which many modern rounds use.
Now, usually smokeless powder doesn't even detonate.
Instead, it deflagrates.
Technically, an explosion is only a detonation
when the material or the gases expelled travel faster than the speed of sound.
If the explosion is subsonic, you're only dealing with a deflagration.
Now, we want a bullet's propellant to deflagrate, not detonate,
because we want it to have enough power to move the bullet quickly,
but not release its energy so fast as to damage the gun or ourselves.
Take a look at some smokeless powder lit in the open and slow motion.
It burns very strongly and quickly,
but at all times, the gasses it expels never exceed the speed of sound
and no shock wave is produced. We're looking at deflegration here, not detonation.
To compare, this is nitroglycerin.
It's so fragile, you hit it with a hammer and it detonates.
Even at a slower speed, we can see that all the material immediately explodes.
Consumer fireworks use black powder, gun powder,
and as such, they don't have enough power to really ever be set to detonate.
The same goes for that quarter stick you saw my dad light off.
Those and M80s and cherry bombs
are louder and often illegal, but they burn flash powder, not a high explosive light dynamite.
But that doesn't mean fireworks can't be amazing.
Currently, some of the largest shells in use are 48 inches across.
When exploded in the air, a 48 inch shell
looks like this.
Or like this.
Oh yeah, when they fail to launch and burst on the ground instead, it looks like this.
But let's move on to detonations—no matter what material releases the energy—
whether it's a conventional explosive or a nuclear bomb or an asteroid impact or an earthquake,
they are all commonly measured by saying how much TNT you would have to detonate
to get an equivalently strong explosion.
To give you a sense of scale, here is the detonation of approximately 100 tons
of TNT by a defense contractor disposing of explosives.
Unlike deflegrations, detonations produce a shockwave,
which is just that, a wave made of areas of high pressure and low pressure.
This explosion was so powerful the area of low pressure
had such low pressure that water vapor in the air around it condensed momentarily,
which formed this cloud.
And here's a video of an explosion where the shock wave is particularly visible
as it approaches and hits the camera man.
You can also see shock condensation clouds around these explosions
set off by the United States in Hawaii in 1965.
The US wanted to know nuclear attacks would affect naval ships,
so they detonated an equivalent amount of TNT
on an island with US ships anchored nearby.
This pile contains 500 tons
of TNT waiting to explode.
When it does, it looks like this.
Earlier, the US tested actual nuclear weapons to see how underwater detonations
might affect our ships.
This underwater nuclear explosion is much larger,
the equivalent of not 100 tons of TNT,
not 500 tons, but 8,000 tons.
For comparison, the atomic bomb dropped on Hiroshima
in 1945 exploded with the energy of 15,000 tons of TNT.
The single most physically powerful device ever used by humanity
was the Tsar Bomb.
The Soviet Union tested it in 1961,
far up north away from civilization.
It was detonated two and a half miles above the surface of the earth
to minimize its destruction, which was unprecedented by man.
The Tsar Bomb exploded with the power equivalent
to 50 million tons of TNT.
The mushroom cloud from the Tsar Bomb
extended beyond our normal atmosphere into the mesosphere
and dwarfed the largest clouds from US detonations.
It was so large that comparatively
the bombs dropped on Japan, well, they're on the graph way down there.
But at the end of the day, nothing can beat supernovas,
the explosion of an entire star.
While 50 million tons may sound like a lot, one supernova is estimated
to give off the energy equivalent of ten octillion million tons of TNT.
I leave you with a cannon developed by the US to shoot a normal little cannon ball,
except that it carried a nuclear warhead.
I'm pretty sure you can pick these up at Bass Pro Shop, but regardless,
be sure you're subscribed to Vsauce
so you don't miss anything coming up,
And as always,
thanks for watching.