You know the cliché of the hero walking away from an explosion, walking slowly and trying to look as “cool” as possible while doing so? Well if you ever thought it was an item unrealistic, you are not alone. Surviving an explosion is not as easy as it seems, let’s find out why.
The explosions we see in movies are often exaggerated and more pyrotechnic than the real ones (for example the explosion of Mount Doom in Lord of the Rings). The huge fireballs that we are used to seeing can occur, but more often than not the real danger of an explosion is due to two main factors: the splinters and theshock wave.
Immediately following an explosion, a myriad of hot metal fragments are thrown in every direction. These fragments, sayings shrapnel, are able to penetrate human skin without any difficulty; wounds sustained by an explosion from these shrapnel are the deadliest.
What people sometimes don’t think about (or underestimate) are shock waves. But what exactly is a shock wave? Every time an explosion occurs, air is pushed out, creating a partial vacuum in the atmosphere. Afterwards, the air from the surrounding atmosphere rushes into the void to fill it, thus generating strong winds.
The winds generated by an explosion can be extremely powerful, as well as destructive. A change in atmospheric pressure of just 5 psi (pounds per square inch) can cause gusts of wind with a speed of 250km/h; speeds of this type are enough to bring down a building and throw anyone in the air in the vicinity. A pressure change of 20 psi, on the other hand, would cause a wind of more than 750km/h.
Needless to say, to survive such explosions, our hero would have to be at a considerable safe distance. However, it would be even more complicated to try to survive a nuclear explosion.