Here's why:
* Short vowel sounds are typically quick and sharp. They are often found in words with one syllable and are usually spelled with a single vowel letter.
* Long vowel sounds are typically drawn out and are often spelled with a vowel followed by a silent "e" or a vowel team (like "ea", "ee", "ai").
In "feet", the vowel sound is short and sharp, similar to the vowel sound in "fit" or "bit".