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All other things being equal are there any greater concerns about surviving an underwater explosion versus an explosion in the atmosphere?

For example, if an explosion of an M80 is going to go off 5 meters from me, am I better off being in an open field with said M80, or would it be better to be underwater (just below surface) with the M80, assuming the distance between me and the M80 are equal?

Is there a formula I could use to determine the equivalent dangers of each? perhaps being 50 feet away from an M80 in an open field is equivalent to being 3 feet away under water?

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    $\begingroup$ I'm voting to close this question as off-topic because it is about the survivability of an explosion and not physics. $\endgroup$ – Kyle Kanos Jun 12 '15 at 3:23
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    $\begingroup$ I'm guessing the explosion would be more dangerous underwater, assuming the firework explodes with the same energy. Owing to the water's greater density, the overpressure will be greater, and the impulse response will be shorter lived: i.e. the energy is concentrated into a shorter lifetime spherical wave. Having said this, the water is probably acoustically more dispersive, leading to swifter pulse spreading with distance. So this is an interesting question for a fluid dynamics expert. $\endgroup$ – WetSavannaAnimal Jun 12 '15 at 3:39
  • $\begingroup$ Obviously the survivability of an explosion in water vs air is a matter of physics. Not off topic in any sense. $\endgroup$ – Nathaniel Jun 12 '15 at 11:43
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I did a little reading and my understanding is that explosions underwater at the same distance as one in air will be much more destructive. Water is a much denser medium than air allowing for the shockwaves to propagate faster. The initial shockwave will be followed by a blast of water, again delivering more force than a blast of air.

An interesting situation is that if the explosion is in air you are better off underwater and vise versa, this has to do with only a percentage of shockwaves refracting from one medium to another, while others are reflected at the interface. Here check out this old question: Would being underwater help survive a nuclear bomb?

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  • $\begingroup$ Can you add your source? I would have thought that the explosion would be less dangerous as the force of the explosion has to go through more material (water) than going through the air, the same idea as to why more armor makes a bullet less destructive $\endgroup$ – TruthOf42 Jun 12 '15 at 14:12
  • $\begingroup$ I think you might be confused about a general principle of waves. When something explodes the explosion does not push through the material, instead its ENERGY propagates through the material. When something explodes in water or air the initial shockwave does not move any water, the energy travels through the medium. The only movement of water would be its longitudinal oscillations. As for your other question, armor poses a completely different situation. Armor simply distributes the impact over more area, lessening the pressure of the impact, force remaining the same $\endgroup$ – Drew Jun 12 '15 at 21:20

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