August 8, 2010

How Close are the Guns? How to Calculate How Close a Storm is

"Men go back to the mountains, as they go back to sailing ships at sea, because in the mountains and on the sea they must face up."

 I hate math. Everyone who knows me knows that I am a firm believer in the "when you need to know it, you will learn it," math method. I am the first person to say "I'll never use this," and that has been the case for most math. I normally kick myself when I need some geometry for sewing or something but it normally only takes a minute to look up a formula and figure it out. Not that I hate math itself, I have just never been any good at it. I know that all math is functional but I feel that teachers tend to leave out what we would really ever use certain formulas for. Since I love practical math and this math formula is easy and fun, I thought I share it:

Figuring how close guns are by using the time lapsed between the flash of it and the sound it makes is practically the same as figuring out how close a storm is by counting the seconds between when you see lightning it and when you hear the thunder. I think it is interesting that many movies will have the flash of a cannon and the sound at the same time. If you were any distance away, there would be a discrepancy due to the fact that light travels faster than sound. 

To find out how far away a storm is you would sound how many seconds from after you see a lightning flash until you hear the thunder. You take that number and multiply it by 1080ft (How fast sound travels on average, temperature and medium affect how fast sound travels. At sea level, it is 1125ft.) Then divide that by 5,280 (the number of feet in a mile for us who forget,) and you get how many miles away a storm is.

Ex. 10 seconds x 1080 (How many feet sound travels in a second) / 5,280 (Number of feet in a mile) =  2.045 miles

It roughly equates to a mile every 5 seconds. Remember that for next storm!

Class dismissed!


  1. I expect you to report just how far away I am at the next reenactment. :P

  2. Andy, I'll do that. Just remember, if they are in are you!

  3. Jodi, you should see the rest of the book that came from. I can't imagine knowing all of that!

  4. First time Here!- I would say that i guess you'd make a good history teacher. This is pretty clever!
    Thanks for sharing!


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