Surviving an explosion from inside a car

[rpmblack]

I'm having difficulty trying to figure how to calc a feat specified in the title. How does 1 calc someone surviving a explosion from inside a car? For context the character was driving uncontrollably until going into another car and it prompty exploding. The car shielded them from some of the blast but they still ultimately crashed onto the road with no seat belt.

Feat in question if anyones curious

 

[DarkDragonMedeus]

Cars don't normally "Explode" in this context, they combust. It what you call it when spark ignites all the gasoline in the car. It generates mostly heat rather than force. And when it comes to surviving extreme heat that has little force, it is often measured in watts for tanking heat. Thermal equilibrium also tends to limit the intensity of feats like that. And most importantly, with standing X joules of thermal energy doesn't quite translate to withstanding X joules of overpressure is worth mentioning.

 

[KLOL506]

That just looks like combustion, the interior of the ambulance is largely unharmed.

Combustion is different from an explosion in the fact that explosion has overpressure (AKA a destructive air shockwave that is able to level tough concrete structures) which combustion doesn't.

 

[rpmblack]

Cars don't normally "Explode" in this context, they combust. It what you call it when spark ignites all the gasoline in the car. It generates mostly heat rather than force. And when it comes to surviving extreme heat that has little force, it is often measured in watts for tanking heat. Thermal equilibrium also tends to limit the intensity of feats like that. And most importantly, with standing X joules of thermal energy doesn't quite translate to withstanding X joules of overpressure is worth mentioning.

Could you give me steps on how to do that here and or an example? Would this even be viable as a note worthy feat for the people inside?

 

[rpmblack]

bump

 

[DarkDragonMedeus]

Step one is this calculator. Temperature of gas burning would be 815 degrees C or about 1088.15 K. Emissivity of a human body is 0.92, and roughly 1.34 m^2 is the average surface area of a human. This comes out at 98001 watts. This is lower than thermal equilibrium, so probably not going to be relevant. But in more extreme temperatures such as surviving inside the center of the sun, those are cases where equilibrium would be less than boltzmann calculator and thus would be the relevant end. To prove equilibrium of your example, multiply mass of a human (Average is 70 kg) by specific heat capacity of a human (About 2980 Joules/(kg*K)), and change in temperature (815-37=778). The result would be 162290800 Joules, but since it would take 162290800/98001 = 1656 seconds to actually reach that, it's not really relevant. In fact, it looks like the fire was only a fraction of a second (Like 600 to 1200 microseconds). So the actual durability is probably in the 10-B range, like 58.8 to 117.6 Joules respectively. This doesn't take the fires that remain into account, which last longer but not anywhere near as hot as the initial spark. And again, this would all simply translate how much thermal energy withstanding. Not quite translating to punches, body slams, or grenade explosions on those levels.

 

[rpmblack]

. And again, this would all simply translate how much thermal energy withstanding. Not quite translating to punches, body slams, or grenade explosions on those levels.

Damn. well thank you anyway