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/sci/ - Science & Math

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5934000 No.5934000 [Reply] [Original]

So I recently had a discussion about superheroes with a pal and one thing that kept coming up was stuff like "impenetrable supersuits" that can withstand any bullets while being elastic.

So I did the math:

I assumed the inpenetrable suit combined with human flesh and boine would allow the bullet to penetrate 1 cm deep into the body (which is far) and decelerate completely.
The average M16 rifle accelerates a 4gramm 5.56 NATO round to 980 m/s
doing rough approximations (this is very rough I know) i figured the bullet would have a kinetic energy of 3.92 J and enact a force of 392 Newtons upon a body.

now my research has not turned up anything on the force the standard human rib or spinal-column (which was the center of the discussion)

can anyone come up with some data on this?

>> No.5934048

I'm not even sure my data is right, is 1cm even realistic for a bone to break?

Also what I mean to say
>now my research has not turned up anything on the force the standard human rib or spinal-column (which was the center of the discussion) can withstand before breaking

>> No.5934113

>>5934000
1 cm is not nearly deep enough to break a rib, ribs flex more than that everytime you take a breath, and 3.93J seems really low.

>> No.5934127

Yea, its 0.5 * mass * velocity * velocity for kenetic energy, so 0.5 * 0.004 * 980 * 980 which is 1920.8J more or less.

>> No.5934137

>>5934113
well i applied m*a (factoring negative decelleration in the time that it takes the bullet to travel 0.01m) AND also kinetic energy, considering that at a full 100% decellartion, the bullet would loose all its energy anyways.

For the values of 4 gramms and 980 m/s that still holds up.
but yeah, recalculating with 3-5cm would probably be more accurate.

Still not sure about specific values of bone elastic to plastic flexibility

>> No.5934145

>>5934127
>>5934137

oops, oversaw the 2, i knew something was off
sorry for that.

so we have about 1000 times higher values for force.