Tags: math

Distant Thunder

So last night while Dyson and I were traveling to and from Wal-Mart, I saw distant clouds illuminated by lighting. This got me to thinking about thunder. I've heard the saying of 'for every second you count after seeing the flash, the lighting was that many miles away'.

The scientific part of my brain would not accept that(despite I don't know how many times before accepting it). It knew that while the speed of sound was much slower than the speed of light, it didn't think it was that slow(effectively 60 miles per second). After all, if it were that slow, I'd be doing Mach 1+ any time I got on the highway!

Thanks to Wikipedia, I found the speed of sound to be an average of about 761 mph. So, that gives us:

761 miles
----------
  1 hour    , we know that 1 hour = 60 minutes = 3600 seconds. Therefore,

   761 miles
--------------  = .21 miles/second( or 370 yards/second or 1109 feet/second).
3600 seconds

So, the real answer is far from the saying. For approximately every 5 seconds between the lighting and the thunder, there is a mile of distance from you and the strike. Of course, one could always just go to the Wikipedia page on thunder and get it from there, but what's the fun in that?