I don't know why you need to know, but after a quick look in the database I found the table 'fileversions' and the attribute 'fvPrefix'. If you explode 'fvPrefix' values into groups of four characters you get the path in the files directory where the file is stored.

Say you have a file named 'awesome.jpg' and fvPrefix is '123456789012' (in table fileversions) you will find the file in:

root
- files
-- 1234
--- 5678
---- 9012
----- awesome.jpg

There might be an easier way to find the path to the file (and the path might be stated somewhere else too), but that is what I found after three minutes.