Why are "mobile" and "automobile" pronounced differently?

I just came across the words and then I looked them both up in the dictionary app, which shows the word "mobile" pronounces as /'məʊbaɪl/, whereas the other word-"automobile", which ends with the same spelt "mobile" pronounces as /'ɔːtəməbiːl/? I'm not sure if this "mobile" word pronounces differently as shown in the app or they actually pronounce the same?

Solution 1:

Because mobile entered English in the 15th century and underwent the Great Vowel Shift (GVS). The GVS was a series of changes in the pronunciation of English vowels that took place between 1400 and 1700 [Wikipedia]. It must have been pronounced with /iː/ and the GVS changed the vowel /iː/ to /aɪ/ (also see bite, which was pronounced the same as beat before the GVS).

Automobile on the other hand entered English after the GVS and preserved its original vowel.