The pitch of a guitar string is determined by its tension, length, and mass.
* Tension: The tighter the string, the higher the pitch.
* Length: The shorter the string, the higher the pitch.
* Mass: The heavier the string, the lower the pitch.
In the case of two strings that are made of the same material and have the same tension, the shorter string will have the higher pitch. This is because the shorter string has less mass than the longer string, and therefore vibrates more quickly.