Here's why:
* Short vowel sounds are typically found in words where the vowel is followed by one consonant. In "juice," the vowel "u" is followed by the consonant "j."
* Long vowel sounds are usually associated with words where the vowel is followed by two consonants, a vowel, or a silent "e." This is not the case in "juice."
Therefore, the "u" in "juice" makes a short "u" sound, similar to the "u" in "cup."