A guitar string has a number of frequencies at which it will naturally vibrate when it is plucked. These natural frequencies are
known as the harmonics of the guitar string and are related to the length of the guitar string in an inverse relationship. For the first harmonic(also known as the fundamental frequency) the relationship can be expressed by the formula below, where f represents the frequency in cycles per second (Hertz) and L represents the length of the guitar string in meters. The quantity v is about 420 m/s.
Determine the fundamental frequency (f) in hertz (first harmonic) of the string if its length is 0.7 meters.