system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do explosives (grenades, artillery, dynamite, etc.) actually kill you?
gpt
There’s generally three ways. 

The easiest one, which requires the least explosive, is via shrapnel. Basically, you encase the explosive with a material that’s designed to shatter into sharp, deadly shards. When the explosive goes off, these shards are ejected away from it at high speeds, and when they hit a body it causes massive damage by cutting, crushing, and disconnecting various body parts. Shrapnel has a few limitations - structures tend to block it and the lethality of shrapnel decreases with distance. So it’s best used as a precise anti-personnel weapon - hand grenades being a great example. You’re not going to knock down a building with shrapnel alone. But you can kill and maim the people inside and establish yourself in it with shrapnel.

The second way is through heat and fire. This one is where an explosive is used to disperse an incendiary material across an area. Here, the explosive is really the delivery system, and the payload is a slow but hot burning material which then damages and kills through obvious means.

The last way is through air pressure. For this, you’re looking at bigger explosives which have an explosive yield big enough to turn air itself into a lethal weapon. At high yields, explosions create a shockwave. This shockwave can impart a massive force on a person, which can damage or even crush bones and organs depending on the size of the shockwave. A shockwave of about 75-80 G’s will kill some 50% of adults it contacts. This is a more complex calculation, depending on the explosive yield of the bomb and the distance from explosion a person is.


Bombs also destroy structures - even if the shrapnel, heat, and air pressure don’t kill you, a bomb can collapse the structure you are in, crushing you or suffocating you.


There’s also some less conventional bombs which spread toxic or deadly materials throughout an area. For instance, a dirty bomb is one which explodes to spread radioactive material in an area. It’s not a nuclear weapon, but it spreads radioactive substances which can kill. 

Nuclear explosives are a different story, especially within a certain distance. Within a few hundred feet, a human body will be vaporized by the intense electromagnetic energy released by the bomb. The heat and light from these weapons can be more intense than that of the surface of the sun.