Here's why:
* Short vowel sounds are typically quick and sharp. They are often represented by the single letter of the vowel in words.
* Long vowel sounds are typically drawn out and often represented by the vowel letter plus a silent 'e' at the end of the word or a vowel digraph (two vowels together).
The sound in "nut" is a short "u" sound, which is distinct from the long "u" sound in words like "flute" or "cube".