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  • 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 detonationsno 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.

Hey, Vsauce. Michael here, and today I'm in my apartment.

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