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> Some of you may have noticed the nuclear missile video says the explosion took place 10,000 feet above our group of soldiers. Apparently, the video is wrong. The Natural Resources Defense Council checked the numbers and says the explosion, part of Operation PLUMBBOB, was actually at 18,500 feet.

Well, there's actually some pretty good proof here that the explosion was closer than that: I count the time between light and sound to be slightly less than 13 seconds (and voices sound right so I'm assuming the recording is accurate in that respect). That would mean the explosion is about 14 000 feet away from the camera.



Keep in mind that speed of sound is not a constant in air, it varies by temperature and pressure (it's actually slower at altitude). Also, the initial fireball (of perhaps a few thousand feet in radius) would have expanded supersonically. that makes the calculation a bit more complicated.

Edit: Also, I watched the relevant portion of the video a couple more times, it seems like there's a possibility the audio is edited. The video cuts back and forth so it's clearly not a continuous shot, we're just trusting that they kept the timing the same and the audio the same, which seems like a bit much to hope for.


It's mentioned some editing was done to make the wait seem shorter.


If the 18,500 figure refers to feet above sea level, then since most of Nevada is at about 4,500 feet above sea level, . . .


Me too!

distance = 1,116.44 feet/second * 12 seconds = 13,397.28 feet


Significant figures, you have too many of them.


13,397 feet


14,000 feet. Sorry to nitpick! You go with the min of the sigfigs in the expression, which here is 2 = sigfigs(12) < sigfigs(13,397.28) = 7


Ha, don't worry about it.

I was thinking it was the significant digits after the decimal. It's always been my weakness calculation-wise.

How about 14E3 feet? :P


much better!


Or 1.4E4 to put it in proper scientific notation.




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